后四wa 求救

#include <bits/stdc++.h>
using namespace std;
int n;
double t,num;
struct albb{
	double w,m;
}a[10086];
bool cmp(albb xx,albb yy)
{
	return xx.w*yy.m>yy.w*xx.m;
}
int main()
{
	cin>>n>>t;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i].w>>a[i].m;
	}
	sort(a+1,a+n+1,cmp);
	for(int i=1;i<=n;i++)
	{
		if(t==0)
			break;
		if(a[i].w<=t)
		{
			t-=a[i].w;
			num+=a[i].m;
		}
		else
		{
			num+=a[i].m*t*1.0/(a[i].w*1.0);
			break;
		}
	}
	printf("%.2lf",num);
	return 0;
 }