how to create an array of random number, all different from each other?

The program should just print out the elements of the array, which stores random integers between 10 and 30. I wanted the numbers to be different from each other, but my program isn't working, what is wrong with it? thanks CODE:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main(){
const int N=12;
int arr[N],i,j;
srand(time(0));
for(i=0;i<N;i++)
arr[i]=10+rand()%20;

for(i=0;i<N;i++)
{
    for(j=N-1;j==0;j--)
    {
        do
        {
           arr[i]=10+rand()%20;
           if(arr[i]!=arr[j])
             break;
        }
        while(arr[i]==arr[j]);
    }
   printf(">>%d\n",arr[i]);
}