🔢 Day 12

Author: AkashRajpurohit

README.md

@@ -18,6 +18,7 @@
 2. [Maximum Difference Between Node and Ancestor](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/565/week-2-november-8th-november-14th/3525/) ➡️ [CPP Solution](Week2/maxAncestorDiff.cpp)
 3. [Flipping an Image](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/565/week-2-november-8th-november-14th/3526/) ➡️ [CPP Solution](Week2/flipAndInvertImage.cpp)
 4. [Valid Square](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/565/week-2-november-8th-november-14th/3527/) ➡️ [CPP Solution](Week2/validSquare.cpp)
+5. [Permutations II](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/565/week-2-november-8th-november-14th/3528/) ➡️ [CPP Solution](Week2/permuteUnique.cpp)
 
 ## Week 3 🚧
 Coming soon...

Week2/permuteUnique.cpp

@@ -0,0 +1,54 @@
+// Approach 1 - Set
+class Solution {
+private:
+    void permute(set<vector<int>>& s, vector<int>& nums, int start) {
+        if(start == nums.size()) {
+            s.insert(nums);
+        } else {
+            for(int i = start; i < nums.size(); ++i) {
+                swap(nums[i], nums[start]);
+                permute(s, nums, start + 1);
+                swap(nums[i], nums[start]);
+            }
+        }
+    }
+public:
+    vector<vector<int>> permuteUnique(vector<int>& nums) {
+        set<vector<int>> s;
+        permute(s, nums, 0);
+        
+        vector<vector<int>> result(s.begin(), s.end());
+        return result;
+    }
+};
+
+// Approach Two - Map to avoid unnecessary calls
+class Solution {
+private:
+    void permute(map<int, int>& m, vector<vector<int>>& result, vector<int>& temp, int start) {
+        if(start == temp.size()) {
+            result.push_back(vector<int>(temp.begin(), temp.end()));
+        } else {
+            for(auto &x: m) {
+                if(x.second > 0) {
+                    m[x.first] = x.second - 1;
+                    temp[start] = x.first;
+                    permute(m, result, temp, start + 1);
+                    m[x.first] = x.second + 1;
+                }
+            }
+        }
+    }
+public:
+    vector<vector<int>> permuteUnique(vector<int>& nums) {
+        vector<vector<int>> result;
+        map<int, int> m;
+        vector<int> temp(nums.size());
+        
+        for(int num: nums)
+            m[num]++;
+        
+        permute(m, result, temp, 0);
+        return result;
+    }
+};