洛谷 P1208 [USACO1.3]混合牛奶 Mixing Milk

水题

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

const int MAXN = 5e3 + 10;

struct prc
{
	int price, val;
	
}arr[MAXN];

bool cmp(prc a, prc b)
{
	return a.price < b.price;
}
 
int main()
{
	int sum , N, ans = 0;
	cin>>sum>>N;
	
	for(int i = 0; i < N; i++)
		cin>>arr[i].price>>arr[i].val;
		
	sort(arr, arr + N, cmp);
	
	for(int i = 0; i < N; i++)
	{
		if(sum - arr[i].val >= 0)
		{
			ans += arr[i].val * arr[i].price;
			sum -= arr[i].val;
		}
		else
		{
			ans += sum * arr[i].price;
			goto l1;
		}
	}
	
	l1:
		cout<<ans<<endl;
		
	return 0;
}