Permutations 解答

 1 public class Solution {
 2     public List<List<Integer>> permute(int[] nums) {
 3         Arrays.sort(nums);
 4         int length = nums.length;
 5         List<List<Integer>> result = new ArrayList<List<Integer>>();
 6         boolean[] visited = new boolean[length];
 7         
 8         dfs(nums, visited, new ArrayList<Integer>(), result);
 9         return result;
10     }
11     
12     private void dfs(int[] nums, boolean[] visited, List<Integer> record, List<List<Integer>> result) {
13         if (record.size() == nums.length) {
14             if (!result.contains(record))
15                 result.add(new ArrayList<Integer>(record));
16             return;
17         }
18         for (int i = 0; i < nums.length; i++) {
19             if (!visited[i]) {
20                 record.add(nums[i]);
21                 visited[i] = true;
22                 dfs(nums, visited, record, result);
23                 // Restore
24                 record.remove(record.size() - 1);
25                 visited[i] = false;
26             }
27         }
28     }
29 }