PROG-T1030: Rice

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

typedef struct rice{
    double price;
    int qt;
    bool operator < (const rice &rhs)const{
        return price > rhs.price;
    }
}rice;

priority_queue<rice> pile;
int np, nm;

int main(){

    double p, sum;
    int q, want;

    scanf("%d", &np);
    for(int i = 0; i < np; ++i){
        scanf("%lf %d", &p, &q);
        pile.push({p / (double)q, q});
    }
    scanf("%d", &nm);
    for(int i = 0; i < nm; ++i){
        scanf("%d", &want);
        sum = 0;
        while(!pile.empty() && want > 0){
            p = pile.top().price;
            q = pile.top().qt;
            if(want < q){
                sum += p * want;
                pile.push({p, q - want});
                pile.pop();
                want -= q;
            } else {
                sum += p * q;
                want -= q;
                pile.pop();
            }
        }
        printf("%.3f\n", sum);
    }

    return 0;
}