Minimum Dot Product

dot_product.cpp

#include <algorithm>
#include <iostream>

using std::vector;

long long min_dot_product(vector<int> a, vector<int> b) {
    std::sort(a.begin(), a.end());
    std::sort(b.begin(), b.end(), std::greater<int>());
    long long result = 0;
    for (int i = 0; i < a.size(); i++) {
        result += (long long) a[i] * b[i];
    }
    return result;
}

int main() {
    size_t n;
    std::cin >> n;
    vector<int> a(n), b(n);
    for (size_t i = 0; i < n; i++) {
        std::cin >> a[i];
    }
    for (size_t i = 0; i < n; i++) {
        std::cin >> b[i];
    }
    std::cout << min_dot_product(a, b) << std::endl;
}