学步园

WA:

#include<iostream>
#include<queue>
#include<iomanip>

using namespace std;

class Node {
public:
	double ratio, mount,value;

	Node(double r,double m,double v){
		ratio=r;
		mount=m;
		value=v;
	}
	bool operator>(const Node n1)const{
		return ratio < n1.ratio;///值越大，优先级越大
	}
};
int main(int argc, char* argv[])
{
	priority_queue<Node, vector<Node>, greater<Node> > pq;
	int m, n;
	double result, j, f;

	while(cin >> m >> n)
	{
		result = 0.0;
		if(m == -1 || n == -1)
			return 1;//-1 -1 return
		for(int i = 0; i < n; i++)
		{
			cin >> j >> f;
			pq.push(Node(j/f, j, f));//sort
		}
		while(m>0 && !pq.empty())
		{
			if(m >= pq.top().value)
			{				
				result += pq.top().mount;
				m -= (int)pq.top().value;
			}else
			{
				result += m * pq.top().ratio;
				m = 0;
			}
			pq.pop();
		}
		cout << fixed << setprecision(3) << result << endl;
	}
	return 0;
}

AC:

在while循环的开始时加上一条：

while(!pq.empty())
			pq.pop();

不然的话，刚开始没问题，后来才会出现问题，下图是测试的数据：