poj2623

快排，注意保留一位小数。

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

#define maxn 250005

int n;
long long f[maxn], sum;

int main()
{
    //freopen("t.txt", "r", stdin);
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
        scanf("%lld", &f[i]);
    sort(f, f + n);
    if (n & 1)
        printf("%lld.0\n", f[n / 2]);
    else
    {
        sum = 0;
        sum += f[n / 2];
        sum += f[n / 2 - 1];
        if (sum & 1)
            printf("%lld.5\n", sum / 2);
        else
            printf("%lld.0\n", sum / 2);
    }
    return 0;
}