NYOJ824 Greedy Mouse

原題鏈接

郁悶，WA了3次，還沒AC，希望大神幫忙找出錯誤。

#include 
#include 

struct Node{
	int x, y;
	double rate;
};

int cmp(const void *a, const void *b){
	return (*(Node *)b).rate - (*(Node *)a).rate;
}

int main(){
	int m, n, i;
	double s;
	while(scanf("%d%d", &m, &n), m != -1 || n != -1){
		Node *a = (Node *)malloc(sizeof(Node) * n);
		for(i = 0; i != n; ++i){
			scanf("%d%d", &a[i].x, &a[i].y);
			a[i].rate = a[i].x * 1.0 / a[i].y;
		}
		qsort(a, n, sizeof(Node), cmp);
		for(i = s = 0; m > 0 && i < n; ++i){
			if(a[i].y <= m){
				s += a[i].x;
				m -= a[i].y;
			}else{
				s += m * a[i].rate;
				break;
			}
		}
		printf("%.3lf\n", s);
		free(a);
	}
	return 0;
}