题解 | 牛牛的数学作业

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

int main() {
    int T;
    scanf("%d", &T);  

    for (int t = 0; t < T; t++) {
        int n;
        scanf("%d", &n);  

        int arr[n];
        long long sum = 0;
        int max = -1000000000;  
        int min = 1000000000;   

        for (int i = 0; i < n; i++) {
            scanf("%d", &arr[i]);
            sum += arr[i];
            if (arr[i] > max) max = arr[i];
            if (arr[i] < min) min = arr[i];
        }

        int dif = max - min;

        double avg = (double)sum / n;

        double var = 0;
        for (int i = 0; i < n; i++) {
            var += pow(avg - arr[i], 2);
        }
        var /= n;  

        printf("%d %.3f\n", dif, var);
    }

    return 0;
}