题目描述
整数二分
样例
输入:
2 10
6 5
5 6
输入:
2
C++ 代码
#include <cstdio>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
const int N = 1e5 + 10;
typedef pair<int, int> PII;
int a[N];
int n, k;
vector<PII> v;
bool check(int mid)
{
int cnt = 0;
for(auto t : v)
{
int flag = min(t.first, t.second);
if(mid > flag)
continue;
cnt += (t.first/mid)*(t.second/mid); //此处切记不可t.first*t.second/(mid*mid),第一次写就没考虑好
}
if(cnt >= k)
return true;
return false;
}
int main()
{
cin>>n>>k;
int l = 1, r = -1;
for(int i = 1; i <= n; ++i)
{
int h, w;
cin>>h>>w;
r = max(r, h>=w?h:w);
v.push_back({h, w});
}
// cout<<r<<endl;
while(l < r)
{
int mid = (l+r+1)>>1; //因为l = mid,故必须+1,否则进入死循环
if(check(mid))
l = mid;
else
r = mid-1;
}
cout<<r<<endl;
return 0;
}