47. 全排列 II

 1 class Solution {
 2   
 3      public List<List<Integer>> permuteUnique(int[] nums) {
 4          List<List<Integer>> list=new ArrayList<>();
 5          if(nums==null||nums.length==0)
 6              return list;
 7       int[] visited=new int[nums.length];
 8       Arrays.sort(nums);
 9       ans(nums,visited,0,new ArrayList(),list);
10       return list;
11         }
12      public void ans(int[] nums,int[] visited,int index,List<Integer> tmp, List<List<Integer>> list)
13      {
14          if(index==nums.length)
15          {
16              list.add(new ArrayList(tmp));
17          }
18          for(int i=0;i<nums.length;i++)
19          {
20              if(i>0&&nums[i]==nums[i-1]&&visited[i-1]==0)//去重的重点！！！！！
21                  continue;
22             if(visited[i]==1)
23                 continue;
24             visited[i]=1;
25             tmp.add(nums[i]);
26             ans(nums,visited,index+1,tmp,list);
27             tmp.remove(tmp.size()-1);
28             visited[i]=0;
29          }
30      }
31 }