transform

#include <bits/stdc++.h>

using namespace std;

int main() {
    vector<int> a{1, 2, 3, 4, 5};
    vector<int> b{5, 4, 3, 2, 1};
    transform(a.begin(), a.end(), b.begin(), a.begin(), [](int a1, int a2) { return a1 - a2; });
    for(int i : a) cout << i << ' ';
}