Insert some random numbers into an array so that each number appears in the array at most once.

/*
4. Insert some random numbers into an array so that each number appears in the array at most once.
*/
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main()
{
    int n, j = 0, i;
    // array size
    scanf("%d", &n);
    int ar[n], cn_ar[1001] = {0};
    srand(time(NULL));
    // INSERT RANDOM NUMBER and count distinct element
    for (i = 0; i < n; ++i)
    {
        int k;
        k = rand()%10;
        printf("%d ", k);
        if (cn_ar[k] == 0)
        {
            ar[j++] = k;
            cn_ar[k]++;
        }
    }
    printf("\n");
    // print  array
    for (i = 0; i < j; ++i)
        printf("%d ", ar[i]);
    return 0;
}