多处最优服务次序问题

#include<iostream>
#include<algorithm>
using namespace std;
const int lenn=10000;
const int lens=500;
int n,s;
int a[lenn];
int wait[lens];
int find()
{
	int minTime=wait[0];
	int pos=0;
	for ( int i=1; i<s; i++ )
	{
		if ( minTime>wait[i] )
		{
			minTime=wait[i];
			pos=i;
		}
	}
	return pos;
}
int main()
{
	while ( cin>>n>>s )
	{
		int i;
		for ( i=0; i<n; i++ )
		{
			cin>>a[i];
		}
		sort ( a,a+n );
		memset ( wait,0,sizeof ( wait ) );
		double sum=0;
		for ( i=0; i<n; i++ )
		{
			int t=find();
			wait[t]+=a[i];
			sum+=wait[t];
		}
		double res=sum/n;
		printf ( "%.2f\n",res );
	}
	return 0;
}