Baekjoon #28070

#include<bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    const int MAX = 130000;
    vector<int> cnt(MAX + 1);

    auto convert = [&](const string &S) -> int {
        int y = stoi(S.substr(0, 4));
        int m = stoi(S.substr(5, 2));
        return y * 12 + m - 1;
    };

    int N; cin >> N;
    for(int i = 0; i < N; ++i) {
        string u, v; cin >> u >> v;
        cnt[convert(u)] ++;
        cnt[convert(v) + 1] --;
    }
    int mx = 0, ans = 0;
    for(int i = 1; i <= MAX; ++i) {
        cnt[i] += cnt[i - 1];
        if(cnt[i] > mx) {
            mx = cnt[i];
            ans = i;
        }
    }
    int y = ans / 12, m = ans % 12 + 1;
    printf("%04d-%02d", y, m);

    return 0;
}

#include<bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int N; cin >> N;
    vector<pair<string, int>> V;
    for(int i = 0; i < N; ++i) {
        string u, v; cin >> u >> v;
        V.emplace_back(u, 1); // 구간의 시작
        V.emplace_back(v, 2); // 구간의 끝
    }
    sort(V.begin(), V.end());

    int cnt = 0, mx = 0;
    string ans = "";
    for(auto [date, type]: V) {
        if(type == 1) { 
            if(++ cnt > mx) {
                mx = cnt;
                ans = date;
            }
        }
        else {
            -- cnt;
        }
    }
    cout << ans;

    return 0;
}