added permutation_2 problem

Author: Kowsihan-sk

Arrays/(LEETCODE) permutation_2.cpp

@@ -0,0 +1,32 @@
+class Solution {
+public:
+    void dfs(vector<int> v, vector<int> &nums, unordered_map<int, int> &mp, vector<vector<int>> &ans){
+        if(v.size() == nums.size()){
+            ans.push_back(v);
+            return;
+        }
+        
+        for(auto i : mp){
+            if(i.second > 0){
+                v.push_back(i.first);
+                mp[i.first]--;
+                
+                dfs(v, nums, mp, ans);
+                
+                mp[i.first]++;
+                v.pop_back();
+            }
+        }
+    }
+    
+    vector<vector<int>> permuteUnique(vector<int>& nums) {
+        vector<vector<int>> ans;
+        unordered_map<int, int> mp;
+        
+        for(int i = 0; i < nums.size(); i++) mp[nums[i]]++;
+        
+        dfs({}, nums, mp, ans);
+        
+        return ans;
+    }
+};