OpenJ_Bailian - 4110 【贪心】圣诞老人的礼物-Santa Clau’s Gifts

题目链接：https://cn.vjudge.net/problem/OpenJ_Bailian-4110

思路：很简单的贪心，性价比排序，先选性价比高的 。证明略~

#include <iostream>
#include <algorithm>
#include <cstdlib>
using namespace std;
const double eps = 1e-6;
struct Candy {
	int v,w;
	bool operator < (const Candy &c) {
		return (double)v/w > (double) c.v/c.w;
	}
}Candies[101];
int main()
{
	int num;
	double Max,ans = 0;

	cin >> num >> Max;
	for(int i=1;i<=num;i++) 
		cin >> Candies[i].v >> Candies[i].w;

	sort(Candies+1,Candies+num+1);

	for(int i=1;i<=num;i++) {
		if(Max >= Candies[i].w) {
			ans += Candies[i].v;
			Max -= Candies[i].w;
		}
		else {
			ans += Candies[i].v/Candies[i].w * Max;
			break;
		}
	}
	printf("%.1lf",ans);
}