题解 | 牛牛的数学作业

#include <stdio.h>
#include <stdlib.h>

int main() {
    int T;
    scanf("%d", &T);
    while (T--) {
        int n;
        scanf("%d", &n);
        long long* arr = (long long*)malloc(n * sizeof(long long));
        long long max = -1e18, min = 1e18;
        long long sum = 0;
        for (int i = 0; i < n; i++) {
            scanf("%lld", &arr[i]);
            if (arr[i] > max) {
                max = arr[i];
            }
            if (arr[i] < min) {
                min = arr[i];
            }
            sum += arr[i];
        }
        double avg = (double)sum / n;
        double variance = 0;
        for (int i = 0; i < n; i++) {
            variance += (arr[i] - avg) * (arr[i] - avg);
        }
        variance /= n;
        printf("%lld %.3lf\n", max - min, variance);
        free(arr);
    }
    return 0;
}