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Program to print Sum of even and odd elements in an array

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  • Difficulty Level : Easy
  • Last Updated : 13 Sep, 2022
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Prerequisite – Array Basics 
Given an array, write a program to find the sum of values of even and odd index positions separately.

Examples: 

Input : arr = {1, 2, 3, 4, 5, 6}
Output :Even index positions sum 9
        Odd index positions sum 12
Explanation: Here, n = 6 so there will be 3 even 
index positions and 3 odd index positions in an array
Even = 1 + 3 + 5 = 9
Odd =  2 + 4 + 6 = 12

Input : arr = {10, 20, 30, 40, 50, 60, 70}
Output : Even index positions sum 160
        Odd index positions sum 170
Explanation: Here, n = 7 so there will be 3 odd
index positions and 4 even index positions in an array
Even = 10 + 30 + 50 + 70 = 160
Odd = 20 + 40 + 60 = 120 
Recommended Practice

Implementation:

C++




// CPP program to find out
// Sum of elements at even and
// odd index positions separately
#include <iostream>
   
using namespace std;
   
// Function to calculate sum
void EvenOddSum(int arr[], int n)
{
    int even = 0;
    int odd = 0;
    for (int i = 0; i < n; i++) {
        // Loop to find even, odd sum
        if (i % 2 == 0)
            even += arr[i];
        else
            odd += arr[i];
    }
   
    cout << "Even index positions sum " << even;
    cout << "\nOdd index positions sum " << odd;
}
   
// Driver function
int main()
{
    int arr[] = { 1, 2, 3, 4, 5, 6 };
    int n = sizeof(arr) / sizeof(arr[0]);
   
    EvenOddSum(arr, n);
   
    return 0;
}

Java




// Java program to find out
// Sum of elements at even and
// odd index positions separately
import java.io.*;
 
class EvenOddSum {
    public static void main(String args[])
    {
        int arr[] = { 1, 2, 3, 4, 5, 6 };
        int even = 0, odd = 0;
 
        // Loop to find even, odd sum
        for (int i = 0; i < arr.length; i++) {
            if (i % 2 == 0)
                even += arr[i];
            else
                odd += arr[i];
        }
 
        System.out.println("Even index positions sum: " + even);
        System.out.println("Odd index positions sum: " + odd);
    }
}

Python3




# Python program to find out
# Sum of elements at even and
# odd index positions separately
 
# Function to calculate Sum
def EvenOddSum(a, n):
    even = 0
    odd = 0
    for i in range(n):
 
        # Loop to find even, odd Sum
        if i % 2 == 0:
            even += a[i]
        else:
            odd += a[i]
     
    print ("Even index positions sum ", even)
    print ("nOdd index positions sum ", odd)
 
# Driver Function
 
arr = [1, 2, 3, 4, 5, 6]
n = len(arr)
 
EvenOddSum(arr, n)
 
# This code is contributed by Sachin Bisht

C#




// C# program to find out
// Sum of elements at even and
// odd index positions separately
using System;
 
public class GFG {
     
    public static void Main()
    {
        int[] arr = { 1, 2, 3, 4, 5, 6 };
        int even = 0, odd = 0;
 
        // Loop to find even, odd sum
        for (int i = 0; i < arr.Length; i++)
        {
            if (i % 2 == 0)
                even += arr[i];
            else
                odd += arr[i];
        }
 
        Console.WriteLine("Even index positions"
                             + " sum: " + even);
                              
        Console.WriteLine("Odd index positions "
                               + "sum: " + odd);
    }
}
 
// This code is contributed by Sam007.

PHP




<?php
// PHP program to find out
// Sum of elements at even and
// odd index positions separately
 
// Function to calculate sum
function EvenOddSum($arr, $n)
{
    $even = 0;
    $odd = 0;
    for ($i = 0; $i < $n; $i++)
    {
         
        // Loop to find even, odd sum
        if ($i % 2 == 0)
            $even += $arr[$i];
        else
            $odd += $arr[$i];
    }
 
    echo("Even index positions sum " . $even);
    echo("\nOdd index positions sum " . $odd);
}
 
// Driver Code
$arr = array( 1, 2, 3, 4, 5, 6 );
$n = sizeof($arr);
 
EvenOddSum($arr, $n);
 
// This code is contributed by Ajit.
?>

Javascript




<script>
 
// Javascript program to find out
// Sum of elements at even and
// odd index positions separately
 
// Function to calculate sum
function EvenOddSum(arr, n)
{
    let even = 0;
    let odd = 0;
    for (let i = 0; i < n; i++)
    {
     
        // Loop to find even, odd sum
        if (i % 2 == 0)
            even += arr[i];
        else
            odd += arr[i];
    }
 
    document.write("Even index positions sum " + even);
    document.write("<br>" + "Odd index positions sum " + odd);
}
 
// Driver function
    let arr = [ 1, 2, 3, 4, 5, 6 ];
    let n = arr.length;
 
    EvenOddSum(arr, n);
     
// This code is contributed by Mayank Tyagi
 
</script>

Output

Even index positions sum 9
Odd index positions sum 12

Time Complexity: O(length(arr))
Auxiliary Space: 0(1)

Method 2: Using slicing in python:

Calculate sum of all even indices using slicing and repeat the same with odd indices and print sum.

Below is the implementation:

C++




#include <iostream>
using namespace std;
 
// Function to calculate sum
int EvenOddSum(int arr[] , int n)
{
  int even = 0;
  int odd = 0;
 
  // Loop to find even, odd sum
  for (int i = 0; i < n; i++) {
    if (i % 2 == 0)
      even += arr[i];
    else
      odd += arr[i];
  }
  cout<<"Even index positions sum "<<even<<"\n" ;
  cout<<"Odd index positions sum " <<odd;
}
 
int main()
{
  int arr[] = { 1, 2, 3, 4, 5, 6 };
  int n =sizeof(arr)/sizeof(arr[0]);
 
  EvenOddSum(arr, n);
}
 
// This code is contributed by ksrikanth0498.

Java




// Java program to find out sum of elements at even
// and odd index positions separately
 
import java.io.*;
 
class GFG {
 
    // Function to calculate sum
    static void EvenOddSum(int[] arr, int n)
    {
        int even = 0;
        int odd = 0;
 
        // Loop to find even, odd sum
        for (int i = 0; i < n; i++) {
            if (i % 2 == 0)
                even += arr[i];
            else
                odd += arr[i];
        }
        System.out.println("Even index positions sum "
                           + even);
        System.out.print("Odd index positions sum " + odd);
    }
 
    public static void main(String[] args)
    {
        int[] arr = { 1, 2, 3, 4, 5, 6 };
        int n = arr.length;
 
        EvenOddSum(arr, n);
    }
}
 
// This code is contributed by lokeshmvs21.

Python3




# Python program to find out
# Sum of elements at even and
# odd index positions separately
 
# Function to calculate Sum
 
 
def EvenOddSum(a, n):
    even_sum = sum(a[::2])
    odd_sum = sum(a[1::2])
    print("Even index positions sum", even_sum)
    print("Odd index positions sum", odd_sum)
 
 
# Driver Function
 
arr = [1, 2, 3, 4, 5, 6]
n = len(arr)
 
EvenOddSum(arr, n)
 
# This code is contributed by vikkycirus

C#




// C# program to find out sum of elements at even
// and odd index positions separately
using System;
 
public class GFG {
 
    // Function to calculate sum
    static void EvenOddSum(int[] arr, int n)
    {
        int even = 0;
        int odd = 0;
 
        // Loop to find even, odd sum
        for (int i = 0; i < n; i++) {
            if (i % 2 == 0)
                even += arr[i];
            else
                odd += arr[i];
        }
        Console.WriteLine("Even index positions sum "
                          + even);
        Console.WriteLine("Odd index positions sum " + odd);
    }
 
    static public void Main()
    {
 
        // Code
        int[] arr = { 1, 2, 3, 4, 5, 6 };
        int n = arr.Length;
 
        EvenOddSum(arr, n);
    }
}
 
// This code is contributed by lokeshmvs21.

Javascript




<script>
 
// Javascript program to find out
// Sum of elements at even and
// odd index positions separately
 
// Function to calculate sum
function EvenOddSum(arr, n)
{
    let even = 0;
    let odd = 0;
    for (let i = 0; i < n; i++)
    {
     
        // Loop to find even, odd sum
        if (i % 2 == 0)
            even += arr[i];
        else
            odd += arr[i];
    }
 
    document.write("Even index positions sum " + even);
    document.write("<br>" + "Odd index positions sum " + odd);
}
 
// Driver function
    let arr = [ 1, 2, 3, 4, 5, 6 ];
    let n = arr.length;
 
    EvenOddSum(arr, n);
     
    // This code is contributed by avijitmondal1998.
</script>

Output

Even index positions sum 9
Odd index positions sum 12

Time Complexity: O(n) where n is no of elements in given array
Auxiliary Space: 0(1)

This article is contributed by Rishabh Jain. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.


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