题解 | 牛牛的数学作业

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <math.h>
int main() {
    int t;
    scanf("%d",&t);
    while (t--) {
        int num;
        scanf("%d",&num);
        int *arr = (int *) malloc((num+2)*sizeof(int));
        memset(arr, 0,num+2);
        for (int i =1;i<=num;i++){
            int middle;
            scanf("%d",&middle);
            arr[i] = middle;
        }
        int max=INT_MIN;
        int min = INT_MAX;
        int sum =0;
        for(int i =1;i<=num;i++){
            if (arr[i]>max){
                max = arr[i];
            }
            if (arr[i]<min){
                min = arr[i];
            }
            sum +=arr[i];

        }
        int jizhi = max - min;
        double avg = sum / (num*1.0);
        double sum_2=0.0;
        for(int i=1;i<=num;i++){
            sum_2 += pow(arr[i] - avg, 2);
        }
        double fangcha = sum_2/num;
        printf("%d %.3lf\n",jizhi,fangcha); 
        

    }
}

需要注意精度和类型。类型问题会导致精度问题