题解 | 牛牛的数学作业

#include <stdio.h>
#include <stdlib.h>
int cmp(const void *a, const void *b){
    return *(int *)a - *(int *)b;
}

int main() {
    //试卷数量
    int T;
    scanf("%d", &T);

    while (T--) {
        //输入本试卷上数字的个数
        int n;
        scanf("%d", &n);

        //输入n个整数
        int num[n];
        double sum = 0;
        for (int i = 0; i < n; i++){
            int a;
            scanf("%d", &a);
            num[i] = a;
            sum += (double)num[i];
        }

        qsort(num, n, sizeof(int), cmp);
        int jicha = num[n - 1] - num[0];
        double pingjunshu = sum / n;


        double fngchahe = 0;
        for (int j = 0; j < n; j++){
            fngchahe += (((double)num[j] - pingjunshu) * ((double)num[j] - pingjunshu));
        }
        
        double fangcha = fngchahe / n;

        printf("%d %.3f\n", jicha, fangcha);
    }
    return 0;
}