检查给定的数字是偶数还是奇数-yiteyi-C++库

给定一个数字，检查它是偶数还是奇数。

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图片[1]-检查给定的数字是偶数还是奇数-yiteyi-C++库

例如：

Input: 2 Output: evenInput: 5Output: odd

建议：请在“上解决” 实践 “首先，在讨论解决方案之前。

一 简单解决方案 就是除以2后求余数。

C++

                         // A simple C++ program to                       
                         // check for even or odd                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // Returns true if n is                       
                         // even, else odd                       
                         bool                                     isEven(                                     int                                     n) {                                     return                                     (n % 2 == 0); }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 101;                       
                                                 isEven(n) ? cout <<                                     "Even"                                     : cout <<                                     "Odd"                                     ;                       
           
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program program to                       
                         // check for even or odd                       
           
                         class                                     GFG                       
                         {                       
                                                 // Returns true if n is even, else odd                       
                                                 public                                     static                                     boolean                                     isEven(                                     int                                     n)                       
                                                 {                       
                                                 return                                     (n %                                     2                                     ==                                     0                                     );                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 int                                     n =                                     101                                     ;                       
                                                 if                                     (isEven(n) ==                                     true                                     )                       
                                                 System.out.print(                                     "Even"                                     );                       
                                                 else                       
                                                 System.out.print(                                     "Odd"                                     );                       
                                                 }                       
                         }                       
           
                         // This code is contributed by rishabh_jain                       

Python3

                         # A simple Python3 code                       
                         # to check for even or odd                       
           
                         # Returns true if n is even, else odd                       
                         def                                     isEven(n):                       
                                                 return                                     (n                                     %                                     2                                     =                                     =                                     0                                     )                       
                                   
                         # Driver code                       
                         n                                     =                                     101                       
                         print                                     (                                     "Even"                                     if                                     isEven(n)                                     else                                     "Odd"                                     )                       
           
                         # This code is contributed by "Sharad_Bhardwaj".                       

C#

                         // C# program program to                       
                         // check for even or odd                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                                                 // Returns true if n is even, else odd                       
                                                 public                                     static                                     bool                                     isEven(                                     int                                     n)                       
                                                 {                       
                                                 return                                     (n % 2 == 0);                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     n = 101;                       
                                                 if                                     (isEven(n) ==                                     true                                     )                       
                                                 Console.WriteLine(                                     "Even"                                     );                       
                                                 else                       
                                                 Console.WriteLine(                                     "Odd"                                     );                       
                                                 }                       
                         }                       
           
                         // This code is contributed by vt_m                       

PHP

                         <?php                       
                         // A simple PHP program to                       
                         // check for even or odd                       
           
                         // Returns true if n is                       
                         // even, else odd                       
                         function                                     isEven(                                     $n                                     )                       
                         {                       
                                                 return                                     (                                     $n                                     % 2 == 0);                       
                         }                       
           
                         // Driver code                       
                         $n                                     = 101;                       
                         if                                     (isEven != true)                       
                                                 echo                                     "Even"                                     ;                       
                                                 else                       
                                                 echo                                     "Odd"                                     ;                       
           
                         // This code is contributed by Ajit                       
                         ?>                       

Javascript

                         <script>                       
           
                         // A simple Javascript program to                       
                         // check for even or odd                       
           
                         // Returns true if n is                       
                         // even, else odd                       
                         function                                     isEven(n) {                                     return                                     (n % 2 == 0); }                       
           
                         // Driver code                       
           
                                                 let n = 101;                       
                                                 isEven(n) ? document.write(                                     "Even"                                     ) :document.write(                                     "Odd"                                     );                       
           
                         // This code is contributed by Mayank Tyagi                       
           
                         </script>

输出：

Odd

时间复杂性： O（1）

辅助空间： O（1） A. 更好的解决方案 就是使用位运算符。我们需要检查最后一位是否为1。若最后一位是1，那个么这个数字是奇数，否则总是偶数。说明：

 input : 5    // odd   00000101               & 00000001                --------------                   00000001       --------------input : 8     //even   00001000               & 00000001                 --------------                  00000000        --------------

下面是这个想法的实施。

C++

                         // A simple C++ program to                       
                         // check for even or odd                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         // Returns true if n is                       
                         // even, else odd                       
                         bool                                     isEven(                                     int                                     n)                       
                         {                       
                                   
                         // n & 1 is 1, then                       
                         // odd, else even                       
                         return                                     (!(n & 1));                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                         int                                     n = 101;                       
                         isEven(n)? cout <<                                     "Even"                                     :                       
                                                 cout <<                                     "Odd"                                     ;                       
           
                         return                                     0;                       
                         }                       

JAVA

                         // Java program program to                       
                         // check for even or odd                       
           
                         class                                     GFG                       
                         {                       
                                                 // Returns true if n                       
                                                 // is even, else odd                       
                                                 public                                     static                                     boolean                                     isEven(                                     int                                     n)                       
                                                 {                       
                                                 if                                     ((n &                                     1                                     ) ==                                     0                                     )                       
                                                 return                                     true                                     ;                       
                                                 else                       
                                                 return                                     false                                     ;                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 int                                     n =                                     101                                     ;                       
                                                 if                                     (isEven(n) ==                                     true                                     )                       
                                                 System.out.print(                                     "Even"                                     );                       
                                                 else                       
                                                 System.out.print(                                     "Odd"                                     );                       
                                                 }                       
                         }                       
           
                         // This code is contributed by rishabh_jain                       

Python3

                         # A Python3 code program                       
                         # to check for even or odd                       
           
                         # Returns true if n is even, else odd                       
                         def                                     isEven(n):                       
                                   
                                                 # n&1 is 1, then odd, else even                       
                                                 return                                     (                                     not                                     (n &                                     1                                     ))                       
                                   
                         # Driver code                       
                         n                                     =                                     101                                     ;                       
                         print                                     (                                     "Even"                                     if                                     isEven(n)                                     else                                     "Odd"                                     )                       
           
                         # This code is contributed by "Sharad_Bhardwaj".                       

C#

                         // C# program program to                       
                         // check for even or odd                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                                                 // Returns true if n                       
                                                 // is even, else odd                       
                                                 public                                     static                                     bool                                     isEven(                                     int                                     n)                       
                                                 {                       
                                                 if                                     ((n & 1) == 0)                       
                                                 return                                     true                                     ;                       
                                                 else                       
                                                 return                                     false                                     ;                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     n = 101;                       
                                                 if                                     (isEven(n) ==                                     true                                     )                       
                                                 Console.WriteLine(                                     "Even"                                     );                       
                                                 else                       
                                                 Console.WriteLine(                                     "Odd"                                     );                       
                                                 }                       
                         }                       
           
                         // This code is contributed by vt_m.                       

PHP

                         <?php                       
                         // A simple PHP program to                       
                         // check for even or odd                       
                                   
                         // Returns true if n is                       
                         // even, else odd                       
                         function                                     isEven(                                     $n                                     )                       
                         {                       
                                                 return                                     (!(                                     $n                                     & 1));                       
                         }                       
                                   
                         // Driver code                       
                         $n                                     = 101;                       
                         if                                     (isEven(                                     $n                                     ) == true)                       
                                                 echo                                     "Even"                                     ;                       
                         else                       
                                                 echo                                     "Odd"                                     ;                       
                                   
                         // This code is contributed by Smitha                       
                         ?>                       

Javascript

                         <script>                       
                         // A simple JavaScript program to                       
                         // check for even or odd                       
           
                         // Returns true if n is                       
                         // even, else odd                       
                         function                                     isEven(n)                       
                         {                       
                                   
                                                 // n & 1 is 1, then                       
                                                 // odd, else even                       
                                                 return                                     (!(n & 1));                       
                         }                       
           
                         // Driver code                       
                         let n = 101;                       
                         isEven(n)? document.write(                                     "Even"                                     ) :                       
                                                 document.write(                                     "Odd"                                     );                       
           
                         // This code is contributed by Manoj.                       
                         </script>                       

输出：

Odd

时间复杂度：O（1）

辅助空间：O（1）

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