Codeforces Beta Round #62

昨晚做了下比赛就早早地睡了，早上爬起来一看，才蛋疼地发现第二题忘记考虑除0的情况，加了一两行代码，一交就AC了，杯具~~~~~~

sum - ave*n = ( a[n] - ave)* k% + (a[n-1]-ave)*k% + (a[n-2]-ave)*k% + ... + (a[i]-ave)*k%

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <iterator>
#include <queue>
#include <cmath>
using  namespace std;

typedef __int64 lld;


int main() {
//      freopen("c:/aaa.txt", "r", stdin);
        double num[10005], sum[10005], k;
        double ave, maxx;
        int n, i;
        scanf( "%d %lf", &n, &k );
        k /= 100;
        for( i=1; i<=n; ++i ) scanf( "%lf", &num[i] );
        sort( num+1, num+n+1 );
        sum[0] = 0;
        for( i=1; i<=n; ++i ) sum[i] = sum[i-1] + num[i];
		if( k != 0 ) {
			maxx = num[1];
			for( i=2; i<=n; ++i ) {
                ave = (sum[n]/k - (sum[n] - sum[i-1])) / (n/k-(n-i+1));
                if( ave >= num[i-1] && ave <= num[i] ) {
					if( ave > maxx ) maxx = ave;
                }
			}
		} else {
			maxx = sum[n]/n;
		}
        printf( "%.9lf\n", maxx );
        return 0;
}