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Thread: random array permutation
 11152012, 01:16 AM #1Member
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 Jul 2012
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random array permutation
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, ..., (n1)].
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 = n1, n2, ..., 1.
here is my code:
Java 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.Last edited by jwl; 11152012 at 02:55 AM.
 11152012, 09:01 PM #2
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