🙍‍♂️ Day 23

Author: Akash Rajpurohit

README.md

@@ -33,6 +33,7 @@
 
 ## Week 4 🚧
 1. [Unique Morse Code Words](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/567/week-4-november-22nd-november-28th/3540/) ➡️ [CPP Solution](Week4/uniqueMorseRepresentations.cpp)
+2. [House Robber III](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/567/week-4-november-22nd-november-28th/3541/) ➡️ [CPP Solution](Week4/rob.cpp)
 
 ## Week 5 🚧
 Coming soon...

Week4/rob.cpp

@@ -0,0 +1,42 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+private:
+    
+    int robHelper(TreeNode* node, unordered_map<TreeNode*, int>& robMap) {
+        if(node == NULL) return 0;
+        
+        if(robMap.count(node) > 0) return robMap.at(node);
+        
+        
+        int withoutNode = robHelper(node->left, robMap) + robHelper(node->right, robMap);
+        
+        int withNode = node->val;
+        if(node->left) {
+            withNode += robHelper(node->left->left, robMap);
+            withNode += robHelper(node->left->right, robMap);
+        }
+        if(node->right) {
+            withNode += robHelper(node->right->left, robMap);
+            withNode += robHelper(node->right->right, robMap);
+        }
+        
+        robMap[node] = max(withNode, withoutNode);
+        return robMap[node];
+            
+    }
+public:
+    int rob(TreeNode* root) {
+        unordered_map<TreeNode*, int> robMap;
+        return robHelper(root, robMap);
+    }
+};