Submission

Score: 0

User: Gump2011

Problemset: ห้องสมุดเมือง 3M

Language: cpp

Time: 0.003 second

Submitted On: 2026-03-08 11:23:54

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

int main(){
    ios::sync_with_stdio(0), cin.tie(0);
    int n;
    cin >> n;

    vector<ll> x(n), y(n);
    ll k = 0;

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

    ll target = k / 2;

    ll l = 0, r = 2e7, ans = 0;

    while (l <= r){
        ll mid = (l + r) / 2;
        ll ct = 0;

        for(int i=0;i<n;i++){
            if(mid < x[i]){
                continue;
            }
            if(mid >= y[i] - 1){
                ct += (y[i] - x[i]);
            }else{
                ct += (mid - x[i] + 1);
            }
        }

        if(ct > target){
            ans = mid;
            r = mid - 1;
        }else{
            l = mid + 1;
        }
    }
    cout << ans - 1;
}