Pair Sum in Vectors in C++

 #include <iostream>

#include <vector>

using namespace std;

vector<int> pairSum(vector<int> arr, int target) {

    int st = 0, end = arr.size()-1;  // with vectors we can substract but with arrays we can just pass

    int currSum = 0;

    vector<int> ans;

    

    

    while(st < end) {

        currSum = arr[st] + arr[end];

        if(currSum == target) {

            ans.push_back(st);

            ans.push_back(end);

            return ans;

        } else if(currSum > target) {

            end--;

            

        } else{

            st++;

        }

    }

    

    return ans; // this case will never come anyway

    

}

int main()

{

    vector<int> vec = {2, 7, 11, 15};

    int target = 9;

    vector<int> ans = pairSum(vec, target);

    cout << ans[0] << "," << ans[1] << endl;

    

    return 0;

    

}