Miaomiao‘s Geometry

3
3
1 2 3
3
1 2 4
4
1 9 100 10

1.000
2.000
8.000
Hint
For the first sample , a legal answer is [1,2] [2,3] so the length is 1.
For the second sample , a legal answer is [-1,1] [2,4] so the answer is 2.
For the thired sample , a legal answer is [-7,1] , [1,9] , [10,18] , [100,108] so the answer is 8.
 

//15MS	268K
#include<stdio.h>
#include<algorithm>
using namespace std;
double s[57],array[107];
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int n,k=0;
        scanf("%d",&n);
        for(int i=0;i<n;i++)
            scanf("%lf",&s[i]);
        sort(s,s+n);
        for(int i=1;i<n;i++)
        {
            array[k++]=s[i]-s[i-1];
            array[k++]=(s[i]-s[i-1])/2;
        }
        sort(array,array+k);
        for(int i=k-1;i>=0;i--)
        {
            bool flag=1;
            double last=s[0],a=array[i];
            for(int j=1;j<n-1;j++)
            {
                if(last==s[j])continue;
                if(last+a<=s[j])last=s[j];
                else if(s[j]+a<=s[j+1])last=s[j]+a;
                else {flag=0;break;}
            }
            if(flag){printf("%.3lf\n",a);break;}
        }
    }
    return 0;
}