Q.14

#include <iostream>
#include <set>
#include <vector>
using namespace std;

multiset<pair<int, int> > all;

pair<int, int> solve(vector<int> &a, int S) {
    for (int i = 0; i < a.size(); i++) {
        auto pos = all.lower_bound({S - a[i], 0});
        if (pos != all.end() && pos -> first == S - a[i])
            return make_pair(pos -> second, i);
        all.insert({a[i], i});
    }
    return make_pair(-1, -1);
}

int main()
{
    int n, S;
    vector<int> a;
    cin >> n >> S;
    a.resize(n);
    for (int i = 0; i < n; i++)
        cin >> a[i];
    pair<int, int> ans = solve(a, S);
    if (ans.first == -1)
        cout << "No such pairs";
    else
        cout << ans.first << ' ' << ans.second;
    return 0;
}