偶数位置的偶数之和-yiteyi-C++库

给定一个大小为n的数组，问题是求偶数和偶数索引的数之和。 例如：

null

Input :  arr[] = {5, 6, 12, 1, 18, 8}Output : 30Explanation: Here, n = 6 Now here are index and numbers as: index->arr[index]0->5, 1->6, 2->12, 3->1, 4->18, 5->8so, number which are even and are at even indices are: 2->12, 4->18sum = 12+18 = 30Input  : arr[] = {3, 20, 17, 9, 2, 10,                         18, 13, 6, 18}Output : 26Explanation: Here, n = 10Now here are index and numbers as: index->arr[index]0->3, 1->20, 2->17, 3->9, 4->2, 5->10, 6->18, 7->13, 8->6, 9->18 So, number which are even and are at even indices are: 4->2, 6->18, 8->6sum = 2+18+6 = 26

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

C++

                         // C++ implementation to                       
                         // find sum of even numbers                       
                         // at even indices                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         // Function to calculate sum                       
                         // of even numbers at even indices                       
                         int                                     sum_even_and_even_index(                       
                                                 int                                     arr[],                                     int                                     n) {                       
           
                                                 int                                     i = 0, sum = 0;                       
                                   
                                                 // calculating sum of even                       
                                                 // number at even index                       
                                                 for                                     (i = 0; i < n; i+=2) {                       
                                   
                                                 if                                     (arr[i] % 2 == 0) {                       
                                   
                                                 sum += arr[i];                       
                                                 }                       
                                                 }                       
                                   
                                                 // required sum                       
                                                 return                                     sum;                       
                         }                       
           
                         // Driver program to test above                       
                         int                                     main() {                       
                                                 int                                     arr[] = {5, 6, 12, 1, 18, 8};                       
                                                 int                                     n =                                     sizeof                                     (arr) /                                     sizeof                                     (arr[0]);                       
                                                 cout <<                                     "Sum of even numbers at even indices is "                       
                                                 << sum_even_and_even_index(arr, n);                       
                                   
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java implementation to find sum of                       
                         // even numbers at even indices                       
           
                         import                                     java.io.*;                       
           
                         class                                     GFG {                       
                                   
                                                 // Function to calculate sum                       
                                                 // of even numbers at even indices                       
                                                 static                                     int                                     sum_even_and_even_index(                       
                                                 int                                     arr[],                                     int                                     n)                       
                                                 {                       
                                   
                                                 int                                     i =                                     0                                     , sum =                                     0                                     ;                       
                                   
                                                 // calculating sum of even                       
                                                 // number at even index                       
                                                 for                                     (i =                                     0                                     ; i < n; i+=                                     2                                     ) {                       
                                   
                                                 if                                     (arr[i] %                                     2                                     ==                                     0                                     ) {                       
                                                 sum += arr[i];                       
                                                 }                       
                                                 }                       
                                   
                                                 // required sum                       
                                                 return                                     sum;                       
                                                 }                       
           
                                                 // Driver program to test above                       
                                                 public                                     static                                     void                                     main (String[] args) {                       
                                   
                                                 int                                     arr[] = {                                     5                                     ,                                     6                                     ,                                     12                                     ,                                     1                                     ,                                     18                                     ,                                     8                                     };                       
                                                 int                                     n = arr.length;                       
                                                 System.out.println(                                     "Sum of even numbers"                       
                                                 +                                     " at even indices is "                                     +                       
                                                 + sum_even_and_even_index(arr, n));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by vt_m.                       

Python3

                         # python 3 implementation to                       
                         # find sum of even numbers                       
                         # at even indices                       
           
                         # Function to calculate sum                       
                         # of even numbers at even indices                       
                         def                                     sum_even_and_even_index(arr,n):                       
                                   
                                                 i                                     =                                     0                       
                                                 sum                                     =                                     0                       
                                   
                         # calculating sum of even                       
                         # number at even index                       
                                                 for                                     i                                     in                                     range                                     (                                     0                                     ,n,                                     2                                     ):                       
                                                 if                                     (arr[i]                                     %                                     2                                     =                                     =                                     0                                     ) :                       
                                                 sum                                     +                                     =                                     arr[i]                       
                                   
                                                 # required sum                       
                                                 return                                     sum                       
           
           
                         # Driver program to test above                       
                         arr                                     =                                     [                                     5                                     ,                                     6                                     ,                                     12                                     ,                                     1                                     ,                                     18                                     ,                                     8                                     ]                       
                         n                                     =                                     len                                     (arr)                       
                         print                                     (                                     "Sum of even numbers at "                                     ,                       
                                                 "even indices is "                                     ,                       
                                                 sum_even_and_even_index(arr, n))                       
                                   
                         # This code is contributed by Sam007                       

C#

                         // C# implementation to find sum of                       
                         // even numbers at even indices                       
           
                         using                                     System;                       
           
                         class                                     GFG {                       
                                   
                                                 // Function to calculate sum                       
                                                 // of even numbers at even indices                       
                                                 static                                     int                                     sum_even_and_even_index(                       
                                                 int                                     []arr,                                     int                                     n)                       
                                                 {                       
                                   
                                                 int                                     i = 0, sum = 0;                       
                                   
                                                 // calculating sum of even                       
                                                 // number at even index                       
                                                 for                                     (i = 0; i < n; i+=2) {                       
                                   
                                                 if                                     (arr[i] % 2 == 0) {                       
                                   
                                                 sum += arr[i];                       
                                                 }                       
                                                 }                       
                                   
                                                 // required sum                       
                                                 return                                     sum;                       
                                                 }                       
           
                                                 // Driver program to test above                       
                                                 public                                     static                                     void                                     Main () {                       
                                   
                                                 int                                     []arr = {5, 6, 12, 1, 18, 8};                       
                                                 int                                     n = arr.Length;                       
                                                 Console.WriteLine(                                     "Sum of even numbers"                       
                                                 +                                     " at even indices is "                                     +                       
                                                 + sum_even_and_even_index(arr, n));                       
                                                 }                       
                         }                       
           
                         //This code is contributed by vt_m.                       

PHP

                         <?php                       
                         // PHP implementation to                       
                         // find sum of even numbers                       
                         // at even indices                       
           
                         // Function to calculate sum                       
                         // of even numbers at even indices                       
                         function                                     sum_even_and_even_index(                                     $arr                                     ,                                     $n                                     )                       
                         {                       
           
                                                 $i                                     = 0;                                     $sum                                     = 0;                       
                                   
                                                 // calculating sum of even                       
                                                 // number at even index                       
                                                 for                                     (                                     $i                                     = 0;                                     $i                                     <                                     $n                                     ;                                     $i                                     =                                     $i                                     +2) {                       
                                   
                                                 if                                     (                                     $arr                                     [                                     $i                                     ] % 2 == 0) {                       
                                   
                                                 $sum                                     +=                                     $arr                                     [                                     $i                                     ];                       
                                                 }                       
                                                 }                       
                                   
                                                 // required sum                       
                                                 return                                     $sum                                     ;                       
                         }                       
           
                         // Driver Code                       
                         {                       
                                                 $arr                                     =                                     array                                     (5, 6, 12, 1, 18, 8);                       
                                                 $n                                     = sizeof(                                     $arr                                     ) / sizeof(                                     $arr                                     [0]);                       
                                                 echo                                     "Sum of even numbers at "                                     .                       
                                                 "even indices is "                                     ,                       
                                                 sum_even_and_even_index(                                     $arr                                     ,                                     $n                                     );                       
                                   
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by nitin mittal.                       
                         ?>                       

Javascript

                         <script>                       
           
                         // Javascript implementation to                       
                         // find sum of even numbers                       
                         // at even indices                       
           
                         // Function to calculate sum                       
                         // of even numbers at even indices                       
                         function                                     sum_even_and_even_index(                       
                                                 arr, n) {                       
           
                                                 let i = 0, sum = 0;                       
                                   
                                                 // calculating sum of even                       
                                                 // number at even index                       
                                                 for                                     (i = 0; i < n; i += 2)                       
                                                 {                       
                                                 if                                     (arr[i] % 2 == 0)                       
                                                 {                       
                                                 sum += arr[i];                       
                                                 }                       
                                                 }                       
                                   
                                                 // required sum                       
                                                 return                                     sum;                       
                         }                       
           
                         // Driver code                       
                                                 let arr = [5, 6, 12, 1, 18, 8];                       
                                                 let n = arr.length;                       
                                                 document.write(                                     "Sum of even numbers at even indices is "                       
                                                 + sum_even_and_even_index(arr, n));                       
                                   
                         // This code is contributed by Mayank Tyagi                       
           
                         </script>                       

输出：

 Sum of even numbers at even indices is 30

文章版权归作者所有，未经允许请勿转载。

THE END

技术文章