Submission

Score: 0

User: winniecoder1029

Problemset: ห้องสมุดเมือง 3M

Language: cpp

Time: 0.002 second

Submitted On: 2026-03-04 22:39:14

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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    if (!(cin >> n)) return 0;

    long long amount = 0;
    vector<long long> x(n), y(n); 
    for (int i = 0; i < n; i++) {
        cin >> x[i] >> y[i];
        amount += (y[i] - x[i]);
    }

    long long target = amount / 2;
    long long pivot = 0;
    
    // 2^25 = 33,554,432 (Covers the 20,000,000 limit)
    for (long long step = 33554432; step > 0; step /= 2) {
        long long testPivot = pivot + step;
        long long Lbook = 0;
        
        for (int i = 0; i < n; i++) {
            if (x[i] < testPivot) {
                // Count elements in [x[i], y[i]) that are < testPivot
                Lbook += min(y[i], testPivot) - x[i];
            }
        }
        
        if (Lbook <= target) {
            pivot += step;
        }
    }

    cout << pivot << endl;
    return 0;
}