Codigos/557B.cpp at master · tfarnecim/Codigos · GitHub

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#include <bits/stdc++.h>
using namespace std;

int main(){

	long long n,w;

	cin >> n >> w;

	long long n2 = n*2;

	long long arr[n2];

	for(long long i=0;i<n2;i++){

		cin >> arr[i];

	}

	sort(arr,arr+n2);

	double fim = ((2.0/3.0) * w)/(double)n;
	double ini = 0;

	while(fim - ini > 0.00000000000001){

		double mid = (fim+ini)/2.0;

		bool aguenta = true;

		for(int i=0;i<n;i++){
			if(arr[i]<mid/2.0){
				aguenta = false;
				break;
			}
		}

		for(int i=n;i<n2;i++){
			if(arr[i]<mid){
				aguenta = false;
				break;
			}
		}

		if(aguenta){
			ini = mid;
		}else{
			fim = mid;
		}

	}

	printf("%.20lf\n",ini * n + (ini/2) * n);

	return 0;
}