简单的排个序

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
int m;
string id, in_time, out_time;

// 把时间(24小时制)转换成整数(以秒为单位)
int conv(const string t) {
    const int h = stoi(t.substr(0, 2)); 
    const int m = stoi(t.substr(3, 2));
    const int s = stoi(t.substr(6, 2));
    return h * 3600 + m * 60 + s;
}

int main(int argc, char** argv) {
    cin >> m;
    vector<pair<int, string>> sign_in, sign_out;
    while (m--) {
        cin >> id >> in_time >> out_time;
        sign_in.emplace_back(conv(in_time), id);
        sign_out.emplace_back(conv(out_time), id);
    }

    sort(begin(sign_in),  end(sign_in));
    sort(begin(sign_out), end(sign_out));
    cout << sign_in.front().second << ' ' << sign_out.back().second << endl;
    return 0;
}