920B - Tea Queue - CodeForces Solution

#include <bits/stdc++.h>
#define HudaYasser ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
int main() {
    HudaYasser
    int t;
    cin>>t;
    while(t--)
    {
        int n,counter=0;
        cin >> n;
        vector<pair<int, int>> v(n);
        for (int i = 0; i < n; i++)
            cin >> v[i].first >> v[i].second;
        for (int i = 0; i < n; i++)
        {
            counter++;
            if(v[i].first>counter)
                counter=v[i].first;
            if(v[i].second<counter)
            {
                cout<<"0"<<" ";
                counter--;
            }
            else
                cout<<counter<<" ";
        }
        cout<<'\n';
    }
    return 0;
}