洛谷P2240 【深基12.例1】部分背包问题进阶解法

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

using namespace std;
struct SCoin
{
	int m, v;
}coin[101];
int N, T, t;
double V;

bool myCompare(const SCoin& first, const SCoin& second)
{
	return first.v * second.m > second.v * first.m;
}

int main()
{
	cin >> N >> T;
	for (int i = 0; i < N; i++)
		cin >> coin[i].m >> coin[i].v;
	sort(coin, coin + N, myCompare);
	for (int i = 0; i < N; i++)
	{
		if (T >= t + coin[i].m)
		{
			V += coin[i].v;
			t += coin[i].m;
		}
		else
		{
			V += (T - t) * (coin[i].v * 1.0) / (coin[i].m * 1.0);
			break;
		}
	}
	cout << fixed << setprecision(2) << V;
	return 0;
}