算法1-3~4 将数组中元素反转存放

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#include<stdio.h>
#include<stdlib.h>
int main(){
    int n;
    scanf("%d",&n);
    int *arr = (int *)calloc(n,sizeof(int));
    if(NULL == arr){
        perror("calloc memory for arr is failed");
        exit(-1);
    }
    for(int i = 0;i < n;i++){
        scanf("%d",&arr[i]);  //注意不要写成scanf("%d ",&arr[i])，留出来的空格会匹配任意数量的空白字符
    }                          //这意味着scanf会一直等待输入   
    int temp = 0;
    for(int i = 0;i < n/2;i++){
        temp = arr[n-1-i];
        arr[n-1-i] = arr[i];
        arr[i] = temp;
    }
    for(int i = 0;i < n;i++){
        printf("%d ",arr[i]);
    }
    free(arr); //注意释放内存
    return 0;
}