分巧克力_二分

P1323 - [蓝桥杯2017初赛]分巧克力 - New Online Judgehttp://oj.ecustacm.cn/problem.php?id=1323

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 100004;
int n,k;
int H[N]= {0},W[N]= {0};
int check(int x) {
    int cnt = 0;
    for(int i=1; i<=n; i++) {
        int h = H[i]/x;
        int w = W[i]/x;
        cnt += h*w;
        if(cnt >= k) {
            return 1;
        }
    }
    return cnt >= k;
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> k;
    for(int i = 1; i <= n; i++) {
        cin >> H[i] >> W[i];
    }
    int left = 1, right = N;
    while(left < right) {
        int mid = (left + right + 1) >> 1;
        if(check(mid)) {
            left = mid;
        } else {
            right = mid - 1;
        }
    }
    cout << left;
    return 0;
}