Programming Contest - EX1

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int time_to_minutes(string time_str) {
    int hours = stoi(time_str.substr(0, 2));
    int minutes = stoi(time_str.substr(3, 2));

    return (hours - 8) * 60 + minutes;
}

int main() {
    int iter;
    cin>>iter;

    vector<pair<int, int>> requests;
    for (int i = 0; i < iter; i++) {
        string input;
        cin>>input;

        string start_str = input.substr(0, 5);
        string end_str = input.substr(6, 5);

        int start_time = time_to_minutes(start_str);
        int end_time = time_to_minutes(end_str);


        if (start_time > end_time || end_time > 10 * 60 || start_time < 0) {
            continue;
        }

        requests.push_back(make_pair(end_time, start_time));
    }

    sort(requests.begin(), requests.end()); // sort by start time

    int max_requests = 0;
    int end_time = 0;

    int vec_len = requests.size();


    for (int i = 0; i < vec_len; i++) {

        int start_time = requests[i].second;
        int end_time_this = requests[i].first;

        if (start_time >= end_time) { // this request can be granted
            max_requests++;
            end_time = end_time_this;
        }
    }

    cout<<max_requests<<endl;

    return 0;
}