[C++知识库]用LUA（和C++）刷PAT (Advanced Level) ——1070 Mooncake

#include <iostream>
#include <vector>
#include <iomanip>
#include <algorithm>

using namespace std;

struct node{
    float amount;
    float price;
};

bool comp(node a, node b) { return a.price / a.amount > b.price / b.amount; }

int main()
{
    int N, demand;
    cin>>N>>demand;
    vector<node> mooncakes(N);
    float price = 0;
    
    for(int i = 0; i < N; i++)
        scanf("%f", &(mooncakes[i].amount));
    for(int i = 0; i < N; i++)
        scanf("%f", &(mooncakes[i].price));

    sort(mooncakes.begin(), mooncakes.end(), comp);
    for(auto itr = mooncakes.begin(); itr != mooncakes.end(); itr ++)
    {
        if (itr -> amount > demand){
            price += itr -> price * demand / itr -> amount;
            cout<<setiosflags(ios::fixed)<<setprecision(2)<<price<<endl;
            return 0;
        }
        price += itr -> price;
        demand -= itr ->amount;
    }
    
    cout<<setiosflags(ios::fixed)<<setprecision(2)<<price<<endl;
    
}