排队的最短平均时间 nkoj 2183

 

优先队列，没什么好说的。

 

 

#include<iostream>
#include<queue>
#include<functional>
#include<iomanip>
using namespace std;
//n is the people's num,and k is the num of room
int n, k;
priority_queue<double,vector<double>, greater<double> > input,ans;
int main()
{
	while (cin >> n >> k){
		double in,sum=0;
		for (int i = 0; i < n; i++){
			cin >> in;
			input.push(in);
		}
		for (int i = 0; i < k; i++){
			in = input.top();
			sum += in;
			ans.push(in);
			input.pop();
		}
		   while(!input.empty()){
			in= ans.top()+input.top();
			sum += in;
			input.pop();
			ans.pop();
			ans.push(in);
		}
		cout << fixed << setprecision(3) << sum / n << endl;
	}
	return 0;
}