贪心 - PAT B - 1020 月饼 (25 分)

#include<cstdio>
#include<algorithm>
using namespace std;

struct cake{
    double number;
    double total_price;
    double per_price;
}mooncakes[1010];

bool cmp(cake a, cake b){
    return a.per_price > b.per_price;
}

int main(){
    int N;
    double D, profit = 0.0;
    scanf("%d %lf", &N, &D);
    for(int i = 0; i < N; i++){
        scanf("%lf", &mooncakes[i].number);
    }
    for(int i = 0; i < N; i++){
        scanf("%lf", &mooncakes[i].total_price);
        mooncakes[i].per_price = mooncakes[i].total_price / mooncakes[i].number;
    }
    sort(mooncakes, mooncakes + N, cmp);

    double remain = D;
    for(int i = 0; i < N; i++){
        if(mooncakes[i].number < remain){
            profit += mooncakes[i].total_price;
            remain -= mooncakes[i].number;
        }
        else{
            profit += mooncakes[i].per_price * remain;
            remain = 0;
            break;
        }
    }

    printf("%.2f", profit);

    return 0;
}

1.注意 total_price总的售价（亿元） 和 number 数量 （万吨） 可以是小数，从一开始就要用Double存储。

2.double的输入是 %lf， 输出是 %f

3.最后控制输出，控制两位小数

4.字符与数字相互转换 number + '0'