Submission

Score: 100

User: foldnut

Problemset: ห้องสมุดเมือง 3M

Language: cpp

Time: 0.003 second

Submitted On: 2025-11-13 21:46:41

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 105;
int n, sm, a[N], b[N];
bool ok(int x){
    int t = 0;
    for(int i = 0;i<n;i++){
        if(x >= b[i]) t += b[i] - a[i];
        else if(x >= a[i]) t += x - a[i] + 1;
    }
    return t >= sm / 2;
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> n;
    for(int i = 0;i<n;i++) cin >> a[i] >> b[i], sm += b[i] - a[i];
    if(sm == 1) return cout << a[0], 0;
    int l = 0, r = 2e7, ans = -1;
    while(l <= r){
        int md = (l + r) / 2;
        if(ok(md)) ans = md, r = md - 1;
        else l = md + 1;
    }
    cout << ans;
}