蓝桥杯备考：二分答案之砍树

这道题同样是可以分析出来二段性的

上手代码

#include <iostream>
using namespace std;
const int N = 1e6+10;
typedef long long ll;
int a[N];
int n,m;
ll calc(int x)
{
	ll cnt = 0;
	for(int i = 1;i<=n;i++)
	{
		if(x<a[i]) cnt+=a[i]-x;
	}
	return cnt;
}

int main()
{
	cin >> n >> m;
	
	for(int i = 1;i<=n;i++)
	{
		cin >> a[i];
	}
	
	ll l = 0,r = 4e5;
	while(l<r)
	{
		ll mid = (l+r+1)/2;
		if(calc(mid) >= m) l=mid;
		else r=mid-1;
	}
	cout << l << endl;
	
	
	
	
	
	return 0;
}