一个数的阶乘程序-yiteyi-C++库

非负整数的阶乘是所有小于或等于n的整数的乘积。例如，6的阶乘是6*5*4*3*2*1，即720。

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图片[1]-一个数的阶乘程序-yiteyi-C++库

递归解决方案： 阶乘可以使用以下递归公式计算。

  n! = n * (n-1)!  n! = 1 if n = 0 or n = 1

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

下面是factorial的实现。

C++

                         // C++ program to find factorial of given number                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // function to find factorial of given number                       
                         unsigned                                     int                                     factorial(unsigned                                     int                                     n)                       
                         {                       
                                                 if                                     (n == 0)                       
                                                 return                                     1;                       
                                                 return                                     n * factorial(n - 1);                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     num = 5;                       
                                                 cout <<                                     "Factorial of "                       
                                                 << num <<                                     " is "                                     << factorial(num) << endl;                       
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by Shivi_Aggarwal                       

C

                         // C program to find factorial of given number                       
                         #include <stdio.h                       
           
                         // function to find factorial of given number                       
                         unsigned                                     int                                     factorial(unsigned                                     int                                     n)                       
                         {                       
                                                 if                                     (n == 0)                       
                                                 return                                     1;                       
                                                 return                                     n * factorial(n - 1);                       
                         }                       
           
                         int                                     main()                       
                         {                       
                                                 int                                     num = 5;                       
                                                 printf                                     (                                     "Factorial of %d is %d"                                     , num, factorial(num));                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to find factorial of given number                       
                         class                                     Test {                       
                                                 // method to find factorial of given number                       
                                                 static                                     int                                     factorial(                                     int                                     n)                       
                                                 {                       
                                                 if                                     (n ==                                     0                                     )                       
                                                 return                                     1                                     ;                       
           
                                                 return                                     n * factorial(n -                                     1                                     );                       
                                                 }                       
           
                                                 // Driver method                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 int                                     num =                                     5                                     ;                       
                                                 System.out.println(                                     "Factorial of "                                     + num                       
                                                 +                                     " is "                                     + factorial(                                     5                                     ));                       
                                                 }                       
                         }                       

Python3

                         # Python 3 program to find                       
                         # factorial of given number                       
           
                         # Function to find factorial of given number                       
                         def                                     factorial(n):                       
                                   
                                                 if                                     n                                     =                                     =                                     0                                     :                       
                                                 return                                     1                       
                                   
                                                 return                                     n                                     *                                     factorial(n                                     -                                     1                                     )                       
                                   
                         # Driver Code                       
                         num                                     =                                     5                                     ;                       
                         print                                     (                                     "Factorial of"                                     , num,                                     "is"                                     ,                       
                         factorial(num))                       
                                   
                         # This code is contributed by Smitha Dinesh Semwal                       

C#

                         // C# program to find factorial                       
                         // of given number                       
                         using                                     System;                       
           
                         class                                     Test {                       
                                                 // method to find factorial                       
                                                 // of given number                       
                                                 static                                     int                                     factorial(                                     int                                     n)                       
                                                 {                       
                                                 if                                     (n == 0)                       
                                                 return                                     1;                       
           
                                                 return                                     n * factorial(n - 1);                       
                                                 }                       
           
                                                 // Driver method                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     num = 5;                       
                                                 Console.WriteLine(                                     "Factorial of "                       
                                                 + num +                                     " is "                                     + factorial(5));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by vt_m                       

PHP

                         <?php                       
                         // PHP program to find factorial                       
                         // of given number                       
           
                         // function to find factorial                       
                         // of given number                       
                         function                                     factorial(                                     $n                                     )                       
                         {                       
                                                 if                                     (                                     $n                                     == 0)                       
                                                 return                                     1;                       
                                                 return                                     $n                                     * factorial(                                     $n                                     - 1);                       
                         }                       
           
                                                 // Driver Code                       
                                                 $num                                     = 5;                       
                                                 echo                                     "Factorial of "                                     ,                                     $num                                     ,                                     " is "                                     , factorial(                                     $num                                     );                       
           
                         // This code is contributed by m_kit                       
                         ?>                       

Javascript

                         <script>                       
                         // Javascript to find factorial                       
                         // of given number                       
           
                         // function to find factorial                       
                         // of given number                       
                         function                                     factorial(n) {                       
                                                 if                                     (n == 0)                                     return                                     1;                       
                                                 return                                     n * factorial(n - 1);                       
                         }                       
           
                         // Driver Code                       
                         let num = 5;                       
                         document.write(                                     "Factorial of "                                     + num +                                     " is "                                     + factorial(num));                       
           
                         // This code is contributed by Saurabh Jaiswal                       
           
                         </script>                       

输出：

Factorial of 5 is 120

迭代解决方案： 阶乘也可以迭代计算，因为递归对于大数来说代价高昂。这里我们展示了使用for和while循环的迭代方法。 使用For循环

C++

                         // C++ program for factorial of a number                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // function to find factorial of given number                       
                         unsigned                                     int                                     factorial(unsigned                                     int                                     n)                       
                         {                       
                                                 int                                     res = 1, i;                       
                                                 for                                     (i = 2; i <= n; i++)                       
                                                 res *= i;                       
                                                 return                                     res;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     num = 5;                       
                                                 cout <<                                     "Factorial of "                       
                                                 << num <<                                     " is "                       
                                                 << factorial(num) << endl;                       
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by Shivi_Aggarwal                       

C

                         #include <stdio.h>                       
           
                         // function to find factorial of given number                       
                         unsigned                                     int                                     factorial(unsigned                                     int                                     n)                       
                         {                       
                                                 int                                     res = 1, i;                       
                                                 for                                     (i = 2; i <= n; i++)                       
                                                 res *= i;                       
                                                 return                                     res;                       
                         }                       
           
                         int                                     main()                       
                         {                       
                                                 int                                     num = 5;                       
                                                 printf                                     (                       
                                                 "Factorial of %d is %d"                                     , num, factorial(num));                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to find factorial of given number                       
                         class                                     Test {                       
           
                                                 // Method to find factorial of the given number                       
                                                 static                                     int                                     factorial(                                     int                                     n)                       
                                                 {                       
                                                 int                                     res =                                     1                                     , i;                       
                                                 for                                     (i =                                     2                                     ; i <= n; i++)                       
                                                 res *= i;                       
                                                 return                                     res;                       
                                                 }                       
           
                                                 // Driver method                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 int                                     num =                                     5                                     ;                       
                                                 System.out.println(                       
                                                 "Factorial of "                                     + num                       
                                                 +                                     " is "                                     + factorial(                                     5                                     ));                       
                                                 }                       
                         }                       

Python3

                         # Python 3 program to find                       
                         # factorial of given number                       
           
                         # Function to find factorial of given number                       
                         def                                     factorial(n):                       
                                   
                                                 res                                     =                                     1                       
                                   
                                                 for                                     i                                     in                                     range                                     (                                     2                                     , n                                     +                                     1                                     ):                       
                                                 res                                     *                                     =                                     i                       
                                                 return                                     res                       
           
                         # Driver Code                       
                         num                                     =                                     5                                     ;                       
                         print                                     (                                     "Factorial of"                                     , num,                                     "is"                                     ,                       
                         factorial(num))                       
                                   
                         # This code is contributed by Smitha Dinesh Semwal                       

C#

                         // C# program to find                       
                         // factorial of given number                       
                         using                                     System;                       
           
                         class                                     Test {                       
                                                 // Method to find factorial                       
                                                 // of given number                       
                                                 static                                     int                                     factorial(                                     int                                     n)                       
                                                 {                       
                                                 int                                     res = 1, i;                       
           
                                                 for                                     (i = 2; i <= n; i++)                       
                                                 res *= i;                       
                                                 return                                     res;                       
                                                 }                       
           
                                                 // Driver method                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     num = 5;                       
                                                 Console.WriteLine(                       
                                                 "Factorial of "                                     + num                       
                                                 +                                     " is "                                     + factorial(5));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by vt_m                       

PHP

                         <?php                       
           
                         // function to find factorial                       
                         // of given number                       
                         function                                     factorial(                                     $n                                     )                       
                         {                       
                                                 $res                                     = 1;                                     $i                                     ;                       
                                                 for                                     (                                     $i                                     = 2;                                     $i                                     <=                                     $n                                     ;                                     $i                                     ++)                       
                                                 $res                                     *=                                     $i                                     ;                       
                                                 return                                     $res                                     ;                       
                         }                       
           
                         // Driver Code                       
                         $num                                     = 5;                       
                         echo                                     "Factorial of "                                     ,                                     $num                                     ,                                     " is "                                     ,                       
                                                 factorial(                                     $num                                     );                       
           
                         // This code is contributed                       
                         // by anuj_67.                       
                         ?>                       

Javascript

                         <script>                       
                         // JavaScript program to find factorial of given number                       
           
                                                 // Method to find factorial of the given number                       
                                                 function                                     factorial(n)                       
                                                 {                       
                                                 var                                     res = 1, i;                       
                                                 for                                     (i = 2; i <= n; i++)                       
                                                 res *= i;                       
                                                 return                                     res;                       
                                                 }                       
           
                                                 // Driver method                       
                                   
                                                 var                                     num = 5;                       
                                                 document.write(                                     "Factorial of "                                     + num +                                     " is "                                     + factorial(5));                       
           
           
                         // This code is contributed by shivanisinghss2110.                       
           
                         </script>                       

输出：

Factorial of 5 is 120

使用While循环

C

                         // C program for factorial of a number                       
                         #include <stdio.h>                       
           
                         // function to find factorial of given number                       
                         unsigned                                     int                                     factorial(unsigned                                     int                                     n)                       
                         {                       
                                                 if                                     (n == 0)                       
                                                 return                                     1;                       
                                                 int                                     i = n, fact = 1;                       
                                                 while                                     (n / i != n) {                       
                                                 fact = fact * i;                       
                                                 i--;                       
                                                 }                       
                                                 return                                     fact;                       
                         }                       
           
                         int                                     main()                       
                         {                       
                                                 int                                     num = 5;                       
                                                 printf                                     (                                     "Factorial of %d is %d"                                     , num, factorial(num));                       
                                                 return                                     0;                       
                         }                       

C++

                         // C++ program for factorial of a number                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // function to find factorial of given                       
                         // number using while loop                       
                         unsigned                                     int                                     factorial(unsigned                                     int                                     n)                       
                         {                       
                                                 if                                     (n == 0)                       
                                                 return                                     1;                       
                                                 int                                     i = n, fact = 1;                       
                                                 while                                     (n / i != n) {                       
                                                 fact = fact * i;                       
                                                 i--;                       
                                                 }                       
                                                 return                                     fact;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     num = 5;                       
                                                 cout <<                                     "Factorial of "                       
                                                 << num <<                                     " is "                       
                                                 << factorial(num) << endl;                       
                                                 return                                     0;                       
                         }                       
                         // This code is contributed by Shivi_Aggarwal                       

JAVA

                         // Java program to find factorial of given number                       
           
                         class                                     Test {                       
           
                                                 // Method to find factorial of the given number                       
                                                 static                                     int                                     factorial(                                     int                                     n)                       
                                                 {                       
                                                 if                                     (n ==                                     0                                     )                       
                                                 return                                     1                                     ;                       
                                                 int                                     i = n, fact =                                     1                                     ;                       
                                                 while                                     (n / i != n) {                       
                                                 fact = fact * i;                       
                                                 i--;                       
                                                 }                       
                                                 return                                     fact;                       
                                                 }                       
           
                                                 // Driver method                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 int                                     num =                                     5                                     ;                       
                                                 System.out.println(                       
                                                 "Factorial of "                                     + num                       
                                                 +                                     " is "                                     + factorial(                                     5                                     ));                       
                                                 }                       
                         }                       

Python3

                         # Python 3 program to find                       
                         # factorial of given number                       
           
                         # Function to find factorial of given number                       
                         def                                     factorial(n):                       
                                                 if                                     (n                                     =                                     =                                     0                                     ):                       
                                                 return                                     1                       
                                                 i                                     =                                     n                       
                                                 fact                                     =                                     1                       
                                   
                                                 while                                     (n                                     /                                     i !                                     =                                     n):                       
                                                 fact                                     =                                     fact                                     *                                     i                       
                                                 i                                     -                                     =                                     1                       
                                   
                                                 return                                     fact                       
           
                         # Driver Code                       
                         num                                     =                                     5                                     ;                       
                         print                                     (                                     "Factorial of"                                     , num,                                     "is"                                     ,                       
                         factorial(num))                       
                                   
                         # This code is contributed by Smitha Dinesh Semwal                       

C#

                         // C# program to find                       
                         // factorial of given number                       
                         using                                     System;                       
           
                         class                                     Test {                       
                                                 // Method to find factorial                       
                                                 // of given number                       
                                                 static                                     int                                     factorial(                                     int                                     n)                       
                                                 {                       
                                                 if                                     (n == 0)                       
                                                 return                                     1;                       
                                                 int                                     i = n, fact = 1;                       
                                                 while                                     (n / i != n) {                       
                                                 fact = fact * i;                       
                                                 i--;                       
                                                 }                       
                                                 return                                     fact;                       
                                                 }                       
           
                                                 // Driver method                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     num = 5;                       
                                                 Console.WriteLine(                       
                                                 "Factorial of "                                     + num                       
                                                 +                                     " is "                                     + factorial(5));                       
                                                 }                       
                         }                       

Javascript

                         <script>                       
                                                 // JavaScript Program to implement                       
                                                 // the above approach                       
                                                 // function to find factorial of given                       
                                                 // number using while loop                       
                                                 function                                     factorial(n) {                       
                                                 if                                     (n == 0)                       
                                                 return                                     1;                       
                                                 let i = n, fact = 1;                       
                                                 while                                     (Math.floor(n / i) != n) {                       
                                                 fact = fact * i;                       
                                                 i--;                       
                                                 }                       
                                                 return                                     fact;                       
                                                 }                       
           
                                                 // Driver code                       
                                                 let num = 5;                       
                                                 document.write(                                     "Factorial of "                       
                                                 + num +                                     " is "                       
                                                 + factorial(num) +                                     "<br>"                                     );                       
           
                         // This code is contributed by Potta Lokesh                       
           
                                                 </script>                       

输出：

Factorial of 5 is 120

上述迭代解的时间复杂度为O（n）。 单线溶液（使用三元运算符）：

C++

                         // C++ program to find factorial of given number                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         int                                     factorial(                                     int                                     n)                       
                         {                       
                                                 // single line to find factorial                       
                                                 return                                     (n == 1 || n == 0) ? 1 : n * factorial(n - 1);                       
                         }                       
           
                         // Driver Code                       
                         int                                     main()                       
                         {                       
                                                 int                                     num = 5;                       
                                                 cout <<                                     "Factorial of "                                     << num <<                                     " is "                                     << factorial(num);                       
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by shivanisinghss2110                       

C

                         // C++ program to find factorial of given number                       
                         #include <stdio.h>                       
           
                         int                                     factorial(                                     int                                     n)                       
                         {                       
                                                 // single line to find factorial                       
                                                 return                                     (n == 1 || n == 0) ? 1 : n * factorial(n - 1);                       
                         }                       
           
                         // Driver Code                       
                         int                                     main()                       
                         {                       
                                                 int                                     num = 5;                       
                                                 printf                                     (                                     "Factorial of %d is %d"                                     , num, factorial(num));                       
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by  Rithika palaniswamy.                       

JAVA

                         // Java program to find factorial                       
                         // of given number                       
                         class                                     Factorial {                       
           
                                                 int                                     factorial(                                     int                                     n)                       
                                                 {                       
           
                                                 // single line to find factorial                       
                                                 return                                     (n ==                                     1                                     || n ==                                     0                                     ) ?                                     1                                     : n * factorial(n -                                     1                                     );                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 Factorial obj =                                     new                                     Factorial();                       
                                                 int                                     num =                                     5                                     ;                       
                                                 System.out.println(                       
                                                 "Factorial of "                                     + num                       
                                                 +                                     " is "                                     + obj.factorial(num));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Anshika Goyal.                       

Python3

                         # Python 3 program to find                       
                         # factorial of given number                       
           
                         def                                     factorial(n):                       
           
                                                 # single line to find factorial                       
                                                 return                                     1                                     if                                     (n                                     =                                     =                                     1                                     or                                     n                                     =                                     =                                     0                                     )                                     else                                     n                                     *                                     factorial(n                                     -                                     1                                     )                       
           
           
                         # Driver Code                       
                         num                                     =                                     5                       
                         print                                     (                                     "Factorial of"                                     , num,                                     "is"                                     ,                       
                                                 factorial(num))                       
           
                         # This code is contributed                       
                         # by Smitha Dinesh Semwal.                       

C#

                         // C# program to find factorial                       
                         // of the given number                       
                         using                                     System;                       
           
                         class                                     Factorial {                       
           
                                                 int                                     factorial(                                     int                                     n)                       
                                                 {                       
           
                                                 // single line to find factorial                       
                                                 return                                     (n == 1 || n == 0) ? 1 : n * factorial(n - 1);                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 Factorial obj =                                     new                                     Factorial();                       
                                                 int                                     num = 5;                       
           
                                                 Console.WriteLine(                       
                                                 "Factorial of "                                     + num                       
                                                 +                                     " is "                                     + obj.factorial(num));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by vt_m.                       

PHP

                         <?php                       
                         // PHP program to find factorial                       
                         // of given number                       
           
                         function                                     factorial(                                     $n                                     )                       
                         {                       
                                   
                                                 // single line to find factorial                       
                                                 return                                     (                                     $n                                     == 1 ||                                     $n                                     == 0) ? 1:                       
                                                 $n                                     * factorial(                                     $n                                     - 1);                       
                         }                       
           
                                                 // Driver Code                       
                                                 $num                                     = 5;                       
                                                 echo                                     "Factorial of "                                     ,                                     $num                                     ,                                     " is "                                     , factorial(                                     $num                                     );                       
           
                         // This code is contributed by anuj_67.                       
                         ?>                       

Javascript

                         <script>                       
           
                         // JavaScript program to find factorial of given number                       
                         function                                     factorial(n)                       
                         {                       
                                                 // single line to find factorial                       
                                                 return                                     (n == 1 || n == 0) ? 1 : n * factorial(n - 1);                       
                         }                       
           
                         // Driver Code                       
           
                                                 var                                     num = 5;                       
                                                 document.write(                                     "Factorial of "                                     +num +                                     " is "                                     + factorial(num));                       
           
                         // This code is contributed by shivanisinghss2110.                       
           
                         </script>                       

输出：

Factorial of 5 is 120

上述解决方案会导致大量数据溢出。请参考大数阶乘这是一个适用于大量数据的解决方案。如果您在上述代码/算法中发现任何错误，请写评论，或者找到其他方法来解决相同的问题。

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