Method permute

ArrayPermutation.java:2–6

(int[] nums)

class Solution {
    public List<List<Integer>> permute(int[] nums) {
        List<List<Integer>> list = new ArrayList<List<Integer>>();
        permute(nums,0,list);
        return list;       
    }
    public static void swap(int nums[],int x,int y)
    {
        int p = nums[x];