题解 | 牛牛的数学作业

#include<stdio.h>
#include<math.h>

int main()
{
    int t;
    scanf("%d",&t);
    int n;
    while(t--)
    {
        scanf("%d",&n);
        int num[n];
        long long range;
        double variance=0.0;
        int min=1e9;
        int max=-1e9;
        int sum=0;
        for(int i=0;i<n;i++)
        {
            scanf("%d",&num[i]);
            if(num[i]>max)max=num[i];
            if(num[i]<min)min=num[i];
            sum+=num[i];
        }
        range=max-min;
        double aver=sum*1.0/n;
        for(int i=0;i<n;i++)
        {
            variance+=pow((double)num[i]-aver,2);
        }
        variance/=n;
        printf("%lld ",range);
        printf("%.3f\n",variance);
    }
    return 0;
}