[二分][洛谷] P1316 丢瓶盖

水题

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

const int MAXN = 1e5;

int arr[MAXN];

int ans = 0;

int N, M;

bool find(int len)
{
	int rit = 1, ritv = arr[0] + len;

	for(int i = 0; i < N; i++)
	{
		if(arr[i] >= ritv)
		{
			rit ++;
			ritv = arr[i] + len;
		}
		if(rit == M)
			return true;
	}
	return false;
}

void bsearch(int lst)
{
	int fst = 1;

	int mid = (fst + lst) / 2;
	
	while(fst <= lst)
	{
		mid = (fst + lst) / 2;
		
		if(find(mid))
		{
			ans = mid;
			fst = mid + 1;
		}
		else
			lst = mid - 1;
	}
	
	cout<<ans<<endl;
}

int main()
{
	
	cin>>N>>M;
	
	for(int i = 0; i < N; i++)
		cin>>arr[i];
		
	sort(arr, arr + N);
	
	bsearch(arr[N - 1]);

	return 0;
}