求一系列1/1之和的程序！+2/2! + 3/3! + 4/4! +…….+ 不！-yiteyi-C++库

你得到了一系列的1/1！+2/2! + 3/3! + 4/4! +…….+ 不！，求出直到第n项的级数之和。 例如：

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Input :n = 5Output : 2.70833Input :n = 7Output : 2.71806

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

A. 简单解决方案 是一个接一个的计算机术语。对于每个项，找到其对应的阶乘值。一 有效解决方案 就是在同一个循环中进行阶乘计算。

CPP

                         // CPP program to print                       
                         // the sum of series                       
                         #include<bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         // function to calculate                       
                         // sum of given series                       
                         double                                     sumOfSeries(                                     double                                     num)                       
                         {                       
                                                 double                                     res = 0, fact = 1;                       
                                                 for                                     (                                     int                                     i = 1; i <= num; i++)                       
                                                 {                       
                                                 // fact variable store                       
                                                 // factorial of the i                       
                                                 fact = fact * i;                       
           
                                                 res = res + (i / fact);                       
                                                 }                       
                                                 return                                     (res);                       
                         }                       
           
                         // Driver Code                       
                         int                                     main()                       
                         {                       
                                                 double                                     n = 5;                       
                                                 cout <<                                     "Sum: "                                     << sumOfSeries(n);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to print                       
                         // the sum of series                       
           
                         import                                     java.io.*;                       
                         import                                     java.lang.*;                       
           
                         class                                     GFG                       
                         {                       
                                                 public                                     static                                     double                                     sumOfSeries(                                     double                                     num)                       
                                                 {                       
                                                 double                                     res =                                     0                                     , fact =                                     1                                     ;                       
                                                 for                                     (                                     int                                     i =                                     1                                     ; i <= num; i++)                       
                                                 {                       
                                                 // fact variable store                       
                                                 // factorial of the i                       
                                                 fact = fact * i;                       
           
                                                 res = res + (i / fact);                       
                                                 }                       
                                                 return                                     (res);                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     main (String[] args)                       
                                                 {                       
                                                 double                                     n =                                     5                                     ;                       
                                                 System.out.println(                                     "Sum: "                                     + sumOfSeries(n));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by                       
                         // Mohit Gupta_OMG <(0_o)>                       

Python3

                         # Python code to find smallest K-digit                       
                         # number divisible by X                       
           
                         def                                     sumOfSeries(num):                       
                                   
                                                 # Computing MAX                       
                                                 res                                     =                                     0                       
                                                 fact                                     =                                     1                       
                                   
                                                 for                                     i                                     in                                     range                                     (                                     1                                     , num                                     +                                     1                                     ):                       
                                                 fact                                     *                                     =                                     i                       
                                                 res                                     =                                     res                                     +                                     (i                                     /                                     fact)                       
                                   
                                                 return                                     res                       
                                   
           
                         n                                     =                                     5                       
                         print                                     (                                     "Sum: "                                     , sumOfSeries(n))                       
           
                         # Code contributed by                       
                         # Mohit Gupta_OMG <(0_o)>                       

C#

                         // C# program to print the sum of series                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                                                 public                                     static                                     float                                     sumOfSeries(                                     double                                     num)                       
                                                 {                       
                                                 float                                     res = 0, fact = 1;                       
                                                 for                                     (                                     int                                     i = 1; i <= num; i++)                       
                                                 {                       
                                                 // fact variable store                       
                                                 // factorial of the i                       
                                                 fact = fact * i;                       
           
                                                 res = res + (i / fact);                       
                                                 }                       
                                                 return                                     (res);                       
                                                 }                       
           
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     Main ()                       
                                                 {                       
                                                 double                                     n = 5;                       
                                                 Console.Write(                                     "Sum: "                                     + sumOfSeries(n));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by vt_m.                       

PHP

                         <?php                       
                         // PHP program to print                       
                         // the sum of series                       
           
                         // Function to calculate                       
                         // sum of given series                       
                         function                                     sumOfSeries(                                     $num                                     )                       
                         {                       
                                                 $res                                     = 0;                                     $fact                                     = 1;                       
                                                 for                                     (                                     $i                                     = 1;                                     $i                                     <=                                     $num                                     ;                                     $i                                     ++)                       
                                                 {                       
                                                 // fact variable store                       
                                                 // factorial of the i                       
                                                 $fact                                     =                                     $fact                                     *                                     $i                                     ;                       
           
                                                 $res                                     =                                     $res                                     + (                                     $i                                     /                                     $fact                                     );                       
                                                 }                       
                                                 return                                     (                                     $res                                     );                       
                         }                       
           
                         // Driver Code                       
                         $n                                     = 5;                       
                         echo                                     (                                     "Sum: "                                     . sumOfSeries(                                     $n                                     ));                       
           
                         // This code is contributed by Ajit.                       
                         ?>                       

Javascript

                         <script>                       
                         // javascript program to print                       
                         // the sum of series                       
                         function                                     sumOfSeries(num)                       
                         {                       
                                                 var                                     res = 0, fact = 1;                       
                                                 for                                     (i = 1; i <= num; i++)                       
                                                 {                       
                                   
                                                 // fact variable store                       
                                                 // factorial of the i                       
                                                 fact = fact * i;                       
                                                 res = res + (i / fact);                       
                                                 }                       
                                                 return                                     (res);                       
                         }                       
           
                         // Driver Code                       
                         var                                     n = 5;                       
                         document.write(                                     "Sum: "                                     + sumOfSeries(n).toFixed(5));                       
           
                         // This code is contributed by Amit Katiyar                       
                         </script>                       

输出：

Sum: 2.70833

时间复杂度：O（n）

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