C++ Recursion: Sum of array elements using recursion

C++ Recursion: Exercise-1 with Solution

Write a C++ program to find the sum of all elements in an array using recursion.

Sample Solution:

C Code:

#include <iostream> // Including the Input/Output Stream Library

// Recursive function to calculate the sum of array elements
int arraySum(int arr[], int size) {
  // Base case: if the array is empty, return 0
  if (size == 0)
    return 0;

  // Recursive case: return the sum of the last element and the sum of the rest of the array
  return arr[size - 1] + arraySum(arr, size - 1);
}

int main() {
  int nums[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; // Initializing an array of integers
  int size = sizeof(nums) / sizeof(nums[0]); // Determining the size of the array

  std::cout << "Array elements: " << std::endl;
  // Loop through the array elements and display them
  for (size_t i = 0; i < size; i++) {
    std::cout << nums[i] << ' ';
  }

  // Calculate the sum of the array elements using recursion
  int sum = arraySum(nums, size); // Calling the recursive function to get the sum

  std::cout << "\nSum of array elements using recursion: " << sum << std::endl; // Display the sum

  return 0; // Returning 0 to indicate successful execution of the program
}

Sample Output:

Array elements:
1 2 3 4 5 6 7 8 9 10
Sum of array elements using recursion: 55

Explanation:

In the above exercise

• The "arraySum()" function takes an array (arr) and the size of the array (size) as parameters.
• It uses recursion to calculate the sum of the array elements.
• The base case is when the size of the array becomes 0, in which case the function returns 0.
• In the recursive case, the function returns the sum of the last element (arr[size - 1]) and the sum of the rest of the array (arraySum(arr, size - 1)).
• The "main()" function shows how to use the arraySum function by passing an array and printing the sum of its elements.

Flowchart:

CPP Code Editor:

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