leetcode Permutations II

 1 class Solution {
 2 public:
 3     vector<vector<int> > permuteUnique(vector<int> &num) 
 4     {
 5         vector<vector<int> > ans;
 6         if (num.size() == 1)
 7             {ans.push_back(num);return ans;}
 8         
 9         vector<vector<int> > post;
10         vector<int> tmp;
11         vector<int> cur;
12         sort(num.begin(), num.end()); // 排好序
13         for (int i = 0; i < num.size(); ++i)
14         {
15             tmp = num;
16             if (i - 1 >= 0 && tmp[i] == tmp[i - 1]) continue; //如果重复数字就跳过
17             tmp.erase(tmp.begin() + i);
18             post = permuteUnique(tmp);
19             for (int j = 0; j < post.size(); ++j)
20             {
21                 cur = post[j];
22                 cur.insert(cur.begin(), num[i]);
23                 ans.push_back(cur);
24             }
25         }
26         return ans;   
27     }
28 };