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How to find the sum of elements of a Vector using STL in C++?

  • Difficulty Level : Basic
  • Last Updated : 08 Jul, 2021

Given a vector, find the sum of the elements of this vector using STL in C++.
Example: 
 

Input: vec = {1, 45, 54, 71, 76, 12}
Output: 259

Input: vec = {1, 7, 5, 4, 6, 12}
Output: 35

 

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Approach: Sum can be found with the help of accumulate() function provided in STL.
Syntax: 
 

accumulate(first_index, last_index, initial value of sum);

Time Complexity: It is linear in the distance between first_index and last_index i.e if your your vector contains n number of elements between two given indices , the time complexity will be O(n).
 

CPP




// C++ program to find the sum
// of Array using accumulate() in STL
 
#include <bits/stdc++.h>
using namespace std;
 
int main()
{
    // Get the vector
    vector<int> a = { 1, 45, 54, 71, 76, 12 };
 
    // Print the vector
    cout << "Vector: ";
    for (int i = 0; i < a.size(); i++)
        cout << a[i] << " ";
    cout << endl;
 
    // Find the sum of the vector
    cout << "\nSum = "
         << accumulate(a.begin(), a.end(), 0);
    return 0;
}
Output: 
Vector: 1 45 54 71 76 12 

Sum = 259

 

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