How to Find the Sum of All Elements in a List in C++ STL?

In C++, a list is a sequence container provided by the STL library that represents a doubly linked list and allows to store data in non-contiguous memory locations. In this article, we will learn how to find the sum of all elements in a list in C++.

Example:

Input:
myList = {10, 20, 30, 40, 50};

Output: 
The sum of all elements in the list is: 150

Sum of All Elements in a List in C++

To find the sum of all elements in a std::list in C++, we can use the std::accumulate() function provided by the <numeric> header that finds the sum of all the elements in the given range with the variable sum.

Syntax to Find the Sum of All Elements in a List

accumulate(first, last, sum);

Here,

• first and last are iterators pointing to beginning and one position past the end of list respectively.
• sum is initial value of the sum (0 here)

C++ Program to Find the Sum of All Elements in a List

The following program demonstrates how we can use the std::accumulate function to find the sum of all elements in a list in C++.

// C++ program to find the sum of all elements in a list

#include <iostream>
#include <list>
#include <numeric>
using namespace std;

int main()
{
    // Initializing a list of integers
    list<int> myList = { 10, 20, 30, 40, 50 };

    // Finding the sum of all elements
    int result
        = accumulate(myList.begin(), myList.end(),
                     0); // initial value of sum is 0 here

    // Printing the sum of all elements in the list
    cout << "The sum of all elements in the list is : "
         << result;

    return 0;
}

The sum of all elements in the list is : 150

Time Complexity: O(N), where N is the size of the list.
Auxiliary Space: O(1)