View Code of Problem 4038

#include<bits/stdc++.h>
using namespace std;
struct node{
	double x,y;
}a[105];
bool cmp(struct node x,struct node y){
	return x.y/x.x>y.y/y.x;
}
int main(){
	int n,v;
	cin>>n>>v;
	int vi[n],wi[n];
	for(int i=0;i<n;++i){
		cin>>a[i].x>>a[i].y;
	}
	int d=0;double sum=0;
	sort(a,a+n,cmp);
	while(v-a[d].x>0){
		sum+=a[d].y;
		v-=a[d].x;
		d++;
	}
	sum+=(a[d].y/a[d].x*v);
	printf("%.2lf",sum);
	return 0;
}