从偶数到给定偶数的平均数-yiteyi-C++库

给定一个偶数n，求从1到n的偶数的平均值。例如：

null

Input : 10Output : 6Explanation:(2 + 4 + 6 + 8 + 10 )/5= 30/5= 6  Input : 100Output : 51

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

方法1 我们可以通过将每个偶数相加到n，然后用计数除以和来计算平均数。

C++

                         // Program to find average of even numbers                       
                         // till a given even number.                       
                         #include <stdio.h>                       
                                   
                         // Function to calculate the average                       
                         // of even numbers                       
                         int                                     averageEven(                                     int                                     n)                       
                         {                       
                                                 if                                     (n % 2 != 0) {                       
                                                 printf                                     (                                     "Invalid Input"                                     );                       
                                                 return                                     -1;                       
                                                 }                       
                                   
                                                 int                                     sum = 0, count = 0;                       
                                                 while                                     (n >= 2) {                       
                                   
                                                 // count even numbers                       
                                                 count++;                       
                                   
                                                 // store the sum of even numbers                       
                                                 sum += n;                       
                                   
                                                 n = n - 2;                       
                                                 }                       
                                                 return                                     sum / count;                       
                         }                       
                                   
                         // driver function                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 16;                       
                                                 printf                                     (                                     "%d"                                     , averageEven(n));                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Program to find average of even numbers                       
                         // till a given even number.                       
                         import                                     java.io.*;                       
                                   
                         class                                     GFG {                       
                                   
                                                 // Function to calculate the average                       
                                                 // of even numbers                       
                                                 static                                     int                                     averageEven(                                     int                                     n)                       
                                                 {                       
                                                 if                                     (n %                                     2                                     !=                                     0                                     ) {                       
                                                 System.out.println(                                     "Invalid Input"                                     );                       
                                                 return                                     -                                     1                                     ;                       
                                                 }                       
                                   
                                                 int                                     sum =                                     0                                     , count =                                     0                                     ;                       
                                                 while                                     (n >=                                     2                                     ) {                       
                                   
                                                 // count even numbers                       
                                                 count++;                       
                                   
                                                 // store the sum of even numbers                       
                                                 sum += n;                       
                                   
                                                 n = n -                                     2                                     ;                       
                                                 }                       
                                                 return                                     sum / count;                       
                                                 }                       
                                   
                                                 // driver function                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 int                                     n =                                     16                                     ;                       
                                                 System.out.println(averageEven(n));                       
                                                 }                       
                         }                       
                                   
                         /*This code is contributed by Nikita Tiwari.*/                       

Python3

                         # Program to find average of                       
                         # even numbers till a given                       
                         # even number.                       
           
                         # Function to calculate the                       
                         # average of even numbers                       
                         def                                     averageEven(n) :                       
           
                                                 if                                     (n                                     %                                     2                                     !                                     =                                     0                                     ) :                       
                                                 print                                     (                                     "Invalid Input"                                     )                       
                                                 return                                     -                                     1                       
                                   
                                                 sm                                     =                                     0                       
                                                 count                                     =                                     0                       
           
                                                 while                                     (n >                                     =                                     2                                     ) :                       
           
                                                 # count even numbers                       
                                                 count                                     =                                     count                                     +                                     1                       
           
                                                 # store the sum of even                       
                                                 # numbers                       
                                                 sm                                     =                                     sm                                     +                                     n                       
           
                                                 n                                     =                                     n                                     -                                     2                       
                                   
                                                 return                                     sm                                     /                                     /                                     count                       
           
                         # driver function                       
                         n                                     =                                     16                       
                         print                                     (averageEven(n))                       
           
                         # This code is contributed by Nikita Tiwari.                       

C#

                         // C# Program to find average                       
                         // of even numbers till a                       
                         // given even number.                       
                         using                                     System;                       
           
                         class                                     GFG {                       
           
                                                 // Function to calculate the                       
                                                 // average of even numbers                       
                                                 static                                     int                                     averageEven(                                     int                                     n)                       
                                                 {                       
                                                 if                                     (n % 2 != 0) {                       
                                                 Console.Write(                                     "Invalid Input"                                     );                       
                                                 return                                     -1;                       
                                                 }                       
           
                                                 int                                     sum = 0, count = 0;                       
                                                 while                                     (n >= 2) {                       
           
                                                 // count even numbers                       
                                                 count++;                       
           
                                                 // store the sum of even numbers                       
                                                 sum += n;                       
           
                                                 n = n - 2;                       
                                                 }                       
                                                 return                                     sum / count;                       
                                                 }                       
           
                                                 // driver function                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     n = 16;                       
                                                 Console.Write(averageEven(n));                       
                                                 }                       
                         }                       
           
                         /*This code is contributed by vt_m.*/                       

PHP

                         <?php                       
                         // PHP Program to find average of even                       
                         // numbers till a given even number.                       
           
                         // Function to calculate the                       
                         // average of even numbers                       
                         function                                     averageEven(                                     $n                                     )                       
                         {                       
                                                 if                                     (                                     $n                                     % 2 != 0)                       
                                                 {                       
                                                 echo                                     (                                     "Invalid Input"                                     );                       
                                                 return                                     -1;                       
                                                 }                       
           
                                                 $sum                                     = 0;                       
                                                 $count                                     = 0;                       
                                                 while                                     (                                     $n                                     >= 2)                       
                                                 {                       
           
                                                 // count even numbers                       
                                                 $count                                     ++;                       
           
                                                 // store the sum of                       
                                                 // even numbers                       
                                                 $sum                                     +=                                     $n                                     ;                       
           
                                                 $n                                     =                                     $n                                     - 2;                       
                                                 }                       
                                                 return                                     $sum                                     /                                     $count                                     ;                       
                         }                       
           
                                                 // Driver Code                       
                                                 $n                                     = 16;                       
                                                 echo                                     (averageEven(                                     $n                                     ));                       
                                   
                         //This code is contributed by vt_m.                       
                         ?>                       

Javascript

                         <script>                       
           
                         // javascript Program to find average of even numbers                       
                         // till a given even number.                       
           
                                   
                         // Function to calculate the average                       
                         // of even numbers                       
                         function                                     averageEven( n)                       
                         {                       
                                                 if                                     (n % 2 != 0) {                       
                                                 document.write(                                     "Invalid Input"                                     );                       
                                                 return                                     -1;                       
                                                 }                       
                                   
                                                 let sum = 0, count = 0;                       
                                                 while                                     (n >= 2) {                       
                                   
                                                 // count even numbers                       
                                                 count++;                       
                                   
                                                 // store the sum of even numbers                       
                                                 sum += n;                       
                                   
                                                 n = n - 2;                       
                                                 }                       
                                                 return                                     sum / count;                       
                         }                       
                                   
                         // driver function                       
                         let n = 16;                       
                                                 document.write( averageEven(n));                       
                                   
                         // This code is contributed by todaysgaurav                       
           
           
                         </script>                       

输出：

方法2 偶数的平均值只能通过一步计算出来通过使用以下公式：- [n+2]/2其中n是最后一个偶数。 这个公式是如何工作的？ 我们知道在n之前有（n）/2个偶数。例如，在4之前有两个偶数，在6之前有三个偶数。前k个偶数之和为k*（k+1）把k=n/2，我们得到总和前n/2个偶数中的n/2（n/2+1） 平均的 前n/2个偶数（或直到n的偶数）=（n+2）/2

C++

                         // Program to find average of even numbers                       
                         // till a given even nend number.                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
                                   
                         // Function to calculate the average                       
                         // of even numbers                       
                         int                                     averageEven(                                     int                                     n)                       
                         {                       
                                                 if                                     (n % 2 != 0) {                       
                                                 cout<<                                     "Invalid Input"                                     ;                       
                                                 return                                     -1;                       
                                                 }                       
                                   
                                                 return                                     (n + 2) / 2;                       
                         }                       
                                   
                         // driver function                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 16;                       
                                                 cout<<averageEven(n)<<endl;                       
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by noob2000.                       

C

                         // Program to find average of even numbers                       
                         // till a given even number.                       
                         #include <stdio.h>                       
                                   
                         // Function to calculate the average                       
                         // of even numbers                       
                         int                                     averageEven(                                     int                                     n)                       
                         {                       
                                                 if                                     (n % 2 != 0) {                       
                                                 printf                                     (                                     "Invalid Input"                                     );                       
                                                 return                                     -1;                       
                                                 }                       
                                   
                                                 return                                     (n + 2) / 2;                       
                         }                       
                                   
                         // driver function                       
                         int                                     main()                       
                         {                       
                                                 int                                     n = 16;                       
                                                 printf                                     (                                     "%d"                                     , averageEven(n));                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Program to find average of even numbers                       
                         // till a given even number.                       
                         import                                     java.io.*;                       
           
                         class                                     GFG {                       
                                   
                                                 // Function to calculate the average                       
                                                 // of even numbers                       
                                                 static                                     int                                     averageEven(                                     int                                     n)                       
                                                 {                       
                                                 if                                     (n %                                     2                                     !=                                     0                                     ) {                       
                                                 System.out.println(                                     "Invalid Input"                                     );                       
                                                 return                                     -                                     1                                     ;                       
                                                 }                       
           
                                                 return                                     (n +                                     2                                     ) /                                     2                                     ;                       
                                                 }                       
           
                                                 // driver function                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 int                                     n =                                     16                                     ;                       
                                                 System.out.println(averageEven(n));                       
                                                 }                       
                         }                       
           
                         /*This code is contributed by Nikita Tiwari.*/                       

Python3

                         # Python3 program to find average of even                       
                         # numbers till a given even number.                       
           
                         # Function to calculate the                       
                         # average of even numbers                       
                         def                                     averageEven(n) :                       
                                                 if                                     (n                                     %                                     2                                     !                                     =                                     0                                     ) :                       
                                                 print                                     (                                     "Invalid Input"                                     )                       
                                                 return                                     -                                     1                       
                                   
                                                 return                                     (n                                     +                                     2                                     )                                     /                                     /                                     2                       
                                   
                         # Driver function                       
                         n                                     =                                     16                       
                         print                                     (averageEven(n))                       
           
                         # This code is contributed by Nikita Tiwari.                       

C#

                         // C# Program to find average                       
                         // of even numbers till a                       
                         // given even number.                       
                         using                                     System;                       
           
                         class                                     GFG {                       
                                   
                                                 // Function to calculate the                       
                                                 // average of even numbers                       
                                                 static                                     int                                     averageEven(                                     int                                     n)                       
                                                 {                       
                                                 if                                     (n % 2 != 0) {                       
                                                 Console.Write(                                     "Invalid Input"                                     );                       
                                                 return                                     -1;                       
                                                 }                       
           
                                                 return                                     (n + 2) / 2;                       
                                                 }                       
           
                                                 // driver function                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     n = 16;                       
                                                 Console.Write(averageEven(n));                       
                                                 }                       
                         }                       
           
                         /*This code is contributed by vt_m.*/                       

PHP

                         <?php                       
                         // PHP Program to find average of even                       
                         // numbers till a given even number.                       
           
                         // Function to calculate the average                       
                         // of even numbers                       
                         function                                     averageEven(                                     $n                                     )                       
                         {                       
                                                 if                                     (                                     $n                                     % 2 != 0)                       
                                                 {                       
                                                 echo                                     (                                     "Invalid Input"                                     );                       
                                                 return                                     -1;                       
                                                 }                       
           
                                                 return                                     (                                     $n                                     + 2) / 2;                       
                         }                       
           
                                                 // Driver Code                       
                                                 $n                                     = 16;                       
                                                 echo                                     (averageEven(                                     $n                                     ));                       
                                                 return                                     0;                       
           
                         // This code is contributed by vt_m.                       
                         ?>                       

Javascript

                         <script>                       
                         // javascript Program to find average of even numbers                       
                         // till a given even number.                       
                                   
                         // Function to calculate the average                       
                         // of even numbers                       
                         function                                     averageEven( n)                       
                         {                       
                                                 if                                     (n % 2 != 0)                       
                                                 {                       
                                                 document.write(                                     "Invalid Input"                                     );                       
                                                 return                                     -1;                       
                                                 }                       
                                                 return                                     (n + 2) / 2;                       
                         }                       
                                   
                         // driver function                       
                                                 let n = 16;                       
                                                 document.write(averageEven(n));                       
                                   
                         // This code is contributed by Rajput-Ji                       
           
                         </script>                       

输出：

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