Submission

Score: 0

User: Ryuthin94

Problemset: ห้องสมุดเมือง 3M

Language: cpp

Time: 0.002 second

Submitted On: 2026-03-06 09:42:46

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

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

    int n;
    long long s = 0;
    cin >> n;

    vector<pair<long long, long long>> lib(n);
    vector<long long> coords;
    for (int i = 0; i < n; i++)
    {
        cin >> lib[i].first >> lib[i].second;
        coords.push_back(lib[i].first);
        coords.push_back(lib[i].second);
    }
    sort(lib.begin(), lib.end());
    sort(coords.begin(), coords.end());
    coords.erase(unique(coords.begin(), coords.end()), coords.end());

    for (int i = 0; i < n; i++)
    {
        s = s + (lib[i].second - lib[i].first);
    }

    long long t = s / 2;
    long long cumsum = 0;
    for (int i = 0; i + 1 < (int)coords.size(); i++)
    {
        long long left = coords[i];
        long long right = coords[i + 1];
        int cnt = 0;
        for (int j = 0; j < n; j++)
        {
            if (lib[j].first <= left && right <= lib[j].second)
                cnt++;
        }
        long long segment_books = (right - left) * cnt;
        if (cumsum + segment_books >= t)
        {
            long long remaining = t - cumsum;
            cout << left + (remaining - 1) / cnt << endl;
            return 0;
        }
        cumsum += segment_books;
    }
}