题解 | 牛牛的数学作业

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

struct paper{
    int n;
    int a[100000];
};

int main() {
    int T;
    scanf("%d\n",&T);
    struct paper *papers = (struct paper *)malloc(T * sizeof(struct paper));
    if(papers == NULL){
        printf("malloc failed");
        return -1;
    }
    for(int i = 0; i < T; i ++){
        scanf("%d\n",&(papers[i].n));
        for(int j = 0; j < papers[i].n; j ++ ){
            scanf("%d",&(papers[i].a[j]));
        }
    }
    for(int i = 0; i < T; i ++){
        int max = -1000000000;
        int min = 1000000000;
        double san_2 = 0;
        double san = 0;
        for(int j = 0; j < papers[i].n; j ++){
            if(papers[i].a[j] > max){
                max = papers[i].a[j];
            }
            if(papers[i].a[j] < min){
                min = papers[i].a[j];
            }
            san_2 += 1.0 * (papers[i].a[j] * papers[i].a[j]) / papers[i].n;
            san += 1.0 *papers[i].a[j] / papers[i].n;
        }
        int jicha = max - min;
       double fangcha = san_2 - san * san;
        printf("%d %.3lf\n",jicha,fangcha);

    }
    free(papers);
    return 0;
}