random array permutation

[jwl]

hey,

I have been working on this bonus question due tomorrow for more than 4 hours total. This a just a part but I am not making good time with this and I am getting frustrated.

here is part of the question:

Write a function int[] RandomPermutation(int n) to create a random permutation of {0, 1, 2, ×××, (n − 1)}.


1. Create the initialize array nums[] = [0, 1, 2, ..., (n-1)].
2. Create a random number m in the range 0 to i.
3. Exchange nums[m] and nums[i].
4. Repeat steps (2)-(3) for i = n-1, n-2, ..., 1.


here is my code:

package bonus;

import java.util.Random;

public class Bonus {

   public int[] RandomPermutation(int n){
        int[] nums = new int[n];
        Random rand = new Random(0);
        for (int i = 0; i < n; i++) {
            nums[i] = i;
        }
        for (int i = n - 1; i > 0; --i) {
            int m = rand.nextInt(i);
            System.out.println(m);
            System.out.println(nums[m] + " " + i);
        }
        return nums;
     }
 
    public static void main(String[] args) {
     Bonus permutation = new Bonus();
     permutation.RandomPermutation(10);
    }
}

I am about to take a break but i will probably be working on this for the rest of the evening.

OK, I think I got steps one two and four taken care of here. Now I need to implement step 3.

[quad64bit]

And what problems specifically are you having with #3?