9.10字节笔试 算法题T3 100% ---二分+贪心

#include <iostream> 
#include <cstring>
#include <algorithm>
using namespace std;

int n, m;
int a[100010]; 
bool check(int d)
{
	int sum = 0;
	for(int i = 0; i < n / d; i ++)
		for(int j = 1; j <= d; j ++)
			sum += max(0, a[i * d + j] - i);
	
	int t = n / d;
	for(int j = 1; j <= n % d; j ++)
		sum += max(0, a[t * d + j] - t);
	return sum >= m;
}
int main()
{
	cin >> n >> m;
	for(int i = 1; i <= n; i ++) cin >> a[i];
	sort(a + 1, a + n + 1, greater<int>());
	int l = 1, r = n;
	while(l < r)
	{
		int mid = l + r >> 1;
		if(check(mid)) r = mid;
		else l = mid + 1;
	}
	cout << l << endl;
}