19.2.7 [LeetCode 47] Permutations II

 1 class Solution {
 2 public:
 3     vector<vector<int>> permuteUnique(vector<int>& nums) {
 4         set<vector<int>>ans;
 5         ans.insert(vector<int>(1, nums[0]));
 6         for (int i = 1; i < nums.size(); i++) {
 7             set<vector<int>>tmp = ans;
 8             ans.clear();
 9             for (auto j = tmp.begin(); j != tmp.end(); j++) {
10                 vector<int>now = *j;
11                 for (int k = 0; k <= now.size(); k++) {
12                     now.insert(now.begin() + k, nums[i]);
13                     ans.insert(now);
14                     now.erase(now.begin() + k);
15                 }
16             }
17         }
18         return vector<vector<int>>(ans.begin(),ans.end());
19     }
20 };