Codeforces Round #311 (Div. 2)

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

int a[4];

int main(void)  {
    int n;  cin >> n;
    int mn1, mx1, mn2, mx2, mn3, mx3;
    cin >> mn1 >> mx1;
    cin >> mn2 >> mx2;
    cin >> mn3 >> mx3;
    a[3] = mn3; a[2] = mn2;
    int res = n - a[2] - a[3];
    if (res <= mx1) a[1] = res;
    else    {
        a[1] = mx1; res -= a[1];
        if (a[2] + res <= mx2)  a[2] += res;
        else    {
            a[2] = mx2; a[3] += (res - (a[2] - mn2));
        }
    }

    cout << a[1] << " " << a[2] << " " << a[3] << endl;

    return 0;
}

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

const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
const double EPS = 1e-9;
int a[N*2];

int main(void)  {
    int n;  int w;   scanf ("%d%d", &n, &w);
    n *= 2;
    for (int i=1; i<=n; ++i)  {
        scanf ("%d", &a[i]);
    }
    sort (a+1, a+1+n);
    double l = 0.0, r = w;
    double mid = 0.0, ans = 0.0;
    for (int i=1; i<=100; ++i)   {
        mid = (l + r) / 2.0;
        if (mid >= 0 && mid <= a[1] && mid * 2 <= a[n/2+1] && mid * 1.5 * n <= w)    {
            l = mid;
            ans = mid * 1.5 * n;
        }
        else    r = mid;
    }
    printf ("%.6f\n", ans);

    return 0;
}

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

const int N = 1e5 + 10;
int a[N*2];

int main(void)  {
    int n, w;   scanf ("%d%d", &n, &w);
    n *= 2;
    for (int i=1; i<=n; ++i)    scanf ("%d", &a[i]);
    sort (a+1, a+1+n);
    double ans = min (a[1] * 1.0, a[n/2+1] / 2.0);
    ans = min (ans * 3 * n / 2.0, w * 1.0);
    printf ("%.6f\n", ans);

    return 0;
}