Submission

Score: 20

User: winniecoder1029

Problemset: ห้องสมุดเมือง 3M

Language: cpp

Time: 0.003 second

Submitted On: 2026-03-04 21:46:07

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

int main()
{
    int n;
    long long amount = 0;
    cin >> n;
    int x[n], y[n];
    for (int i = 0; i<n; i++) {
        cin >> x[i] >> y[i];
        amount += y[i] - x[i];
    }
    // median = amount >> 1
    
    
    //cout << Lbook;
    //start binary search, while amount > 1
    
    long long pivot = 16777216;
    long long step = pivot/2;  
    long long Lbook = 0;
    while (step >= 1) {
        Lbook = 0;
        for (int i = 0; i<n; i++) {
            if (x[i] < pivot) {
              long long upper = y[i] < pivot ? y[i] : pivot;
              Lbook += upper - x[i];
            } 
        }    
        //cout << "!!" << pivot - step ;
        if (Lbook <= amount/2) {
            pivot += step;
        } else {
            pivot -= step;
        }
        //cout << step <<" , " << pivot << endl;
        step/=2;
        
    }
    
    Lbook = 0;
        for (int i = 0; i<n; i++) {
            if (x[i] < pivot) {
              long long upper = y[i] < pivot ? y[i] : pivot;
              Lbook += upper - x[i];
            } 
        }
    if (Lbook < pivot/2) {
      cout << pivot;
    } else {
      cout << pivot - 1;
    }
    
    
    return 0;
}