STL accumulate()

//Time Complexity of This function (n*k), Here n is size of array or vector and k is complexity of internal function

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cout << "Enter Array Size :: ";
    cin >> n;

    int a[n];

    cout << "\nEnter Array Element :: \n";
    for(int i=0;i<n;i++)
        cin >> a[i];

    int sum = accumulate(a, a+n, 0);

    cout << "\nSummation is :: " << sum << "\n";

    cout << "\nFor Vector :: \n\n";

    cout << "Enter Vector Size :: ";
    cin >> n;

    vector<int>v(n);

    cout << "\nEnter Vector Element :: \n";
    for(int i=0;i<n;i++)
        cin >> v[i];

    sum = accumulate(v.begin(), v.end(), 0);

    cout << "\nSummation is :: " << sum;

    return 0;
}