976C - Nested Segments - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;

bool comp(pair<pair<int,int>,int> &x, pair<pair<int,int>,int> &y){
    if(x.first.first != y.first.first) return x.first.first < y.first.first;
    return x.first.second > y.first.second;
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int n, ans = -1;
    cin >> n;
    pair<pair<int,int>,int> a[n];
    pair<int,int> b;

    for(int i = 0; i < n; i++){
        cin >> a[i].first.first >> a[i].first.second;
        a[i].second = i+1;
    } 
    sort(a, a+n, comp);
    b = {a[0].first.second, a[0].second};

    for(int i = 1; i < n; i++){
        if(b.first >= a[i].first.second){
            ans = a[i].second;
            break;
        }
        b = max(b, {a[i].first.second, a[i].second});
    }
    if(ans != -1) cout << ans << " " << b.second << "\n";
    else cout << "-1 -1";
    
    
    return 0;
}