Permutations II

Given a collection of numbers that might contain duplicates, return all possible unique permutations.

For example,
[1,1,2] have the following unique permutations:
[1,1,2], [1,2,1], and [2,1,1].

public class Solution {
     public List<List<Integer>> permuteUnique(int[] num) {
         List<List<Integer>> result = new ArrayList<List<Integer>>();
         List<Integer> curr = new ArrayList<Integer>();
         Arrays.sort(num);
         dfs(result, curr, num, 0);
         return result;
     }

     void dfs(List<List<Integer>> result, List<Integer> curr, int[] num, int index) {
         if (index == num.length) {
             if (!result.contains(curr)) {
                result.add(new ArrayList<Integer>(curr));

             }
         } else {
             for (int i = index; i <num.length ; i++) {
                 if (noSwap(num,i,index)) {
                     continue;
                 } else {
                     swap(num, i, index);
                 }
                 curr.add(num[index]);
                 dfs(result, curr, num, index + 1);
                 curr.remove(curr.size() - 1);
                 swap(num, index,i );

             }

         }
     }

     void swap(int[] num, int indexA, int indexB) {
         int temp = num[indexA];
         num[indexA] = num[indexB];
         num[indexB] = temp;
     }

     boolean noSwap(int[] num, int i, int j) {
         for (int k = j; k < i; k++) {
             if (num[k] == num[i]) {
                 return true;
             }
         }
         return false;
     }

}