HDOJ2187悼念512汶川大地震遇难同胞(贪心，硬币问题)

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
struct rice{
double price;
double weight;
}a[1010];

int cmp(rice a,rice b){
return a.price <b.price;
}
int main(){
int t;
cin>>t;
while(t--){
int sum,n;
cin>>sum>>n;
int i;
for(i=0;i<n;i++){
cin>>a[i].price >>a[i].weight;
}
sort(a,a+n,cmp);
double k=0;
for(i=0;i<n;i++){
if(sum>a[i].price*a[i].weight){
sum-=a[i].price*a[i].weight ;
k+=a[i].weight;
}
else{
k+=sum/a[i].price;
break;
}
}
printf("%.2lf\n",k);
}
return 0;
}