Sum of array elements using recursion

Given an array of integers, find sum of array elements using recursion.

Examples:

Input : A[] = {1, 2, 3}
Output : 6
1 + 2 + 3 = 6

Input : A[] = {15, 12, 13, 10}
Output : 50

We have discussed iterative solution in below post.
Sum of elements in a given array



In this post, recursive solution is discussed.

C++

// C++ program to find sum of array
// elements using recursion.
#include <stdio.h>

// Return sum of elements in A[0..N-1]
// using recursion.
int findSum(int A[], int N)
{
    if (N <= 0)
        return 0;
    return (findSum(A, N - 1) + A[N - 1]);
}

// Driver code
int main()
{
    int A[] = { 1, 2, 3, 4, 5 };
    int N = sizeof(A) / sizeof(A[0]);
    printf("%dn", findSum(A, N));
    return 0;
}

Java

// Java program to find sum of array
// elements using recursion.

class Test {
    static int arr[] = { 1, 2, 3, 4, 5 };

    // Return sum of elements in A[0..N-1]
    // using recursion.
    static int findSum(int A[], int N)
    {
        if (N <= 0)
            return 0;
        return (findSum(A, N - 1) + A[N - 1]);
    }

    // Driver method
    public static void main(String[] args)
    {
        System.out.println(findSum(arr, arr.length));
    }
}

Python

# Python program to find sum of array
# elements using recursion.

 # Return sum of elements in A[0..N-1]
 # using recursion.
  def _findSum(arr, N):
     if len(arr)== 1:
        return arr[0]
     else:
        return arr[0]+_findSum(arr[1:], N)

# driver code
arr =[]
# input values to list
arr = [1, 2, 3, 4, 5]
 
# calculating length of array
N = len(arr)
 
ans =_findSum(arr,N)
print (ans)
 
# This code is contributed by Khare Ishita

C#

// C# program to find sum of array
// elements using recursion.
using System;

class Test {
    
    static int []arr = {1, 2, 3, 4, 5};

    // Return sum of elements in 
    // A[0..N-1] using recursion.
    static int findSum(int []A, int N)
    {
        if (N <= 0)
            return 0;
        return (findSum(A, N - 1) + A[N - 1]);
    }

    // Driver Code
    public static void Main()
    {
        Console.Write(findSum(arr, arr.Length));
    }
}

// This code is contributed by Nitin Mittal.

PHP


<?php
// PHP program to find sum 
// of array elements using
// recursion.

// Return sum of elements 
// in A[0..N-1] using recursion.
function findSum($A, $N)
{
    if ($N <= 0)
        return 0;
    return (findSum($A, $N - 1) + 
                    $A[$N - 1]);
}

// Driver code
$A = array(1, 2, 3, 4, 5);
$N = sizeof($A);
echo findSum($A, $N);
    
// This code is contributed 
// by ihritik
?>


Output:

15

How does above recursive solution work?

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

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