🌴 Day 9

Author: AkashRajpurohit

README.md

@@ -17,6 +17,7 @@
 ## Week 2 🚧
 
 1. [Binary Search](https://leetcode.com/explore/challenge/card/october-leetcoding-challenge/560/week-2-october-8th-october-14th/3488/) ➡️ [CPP Solution](Week2/search.cpp)
+2. [Serialize and Deserialize BST](https://leetcode.com/explore/challenge/card/october-leetcoding-challenge/560/week-2-october-8th-october-14th/3489/) ➡️ [CPP Solution](Week2/Codec.cpp)
 
 ## Week 3 🚧
 

Week2/Codec.cpp

@@ -0,0 +1,85 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Codec {
+private:
+    char delimiter = ' ';
+    
+    // PreOrder
+    void dfs(TreeNode* root, string& s) {
+        if(root == NULL) return;
+        
+        s.append(to_string(root->val) + delimiter);
+        
+        dfs(root->left, s);
+        dfs(root->right, s);
+    }
+    
+    vector<int> stringToVector(string s) {
+        vector<int> res;
+        int n = s.size();
+        int i = 0;
+        string tmp = "";
+        
+        while(i < n) {
+            
+            while(i < n && s[i] != delimiter) {
+                tmp += s[i];
+                i++;
+            }
+            
+            res.push_back(stoi(tmp));
+            tmp.erase();
+            i++;
+        }
+        
+        return res;
+    }
+    
+    TreeNode* createBST(vector<int> nums, int start, int end) {
+        if(start > end) return NULL;
+        
+        TreeNode* root = new TreeNode(nums[start]);
+        
+        int index;
+        
+        for(index = start; index <= end; ++index) {
+            if(nums[index] > nums[start]) break;
+        }
+        
+        root->left = createBST(nums, start + 1, index - 1);
+        root->right = createBST(nums, index, end);
+        
+        return root;
+    }
+public:
+
+    // Encodes a tree to a single string.
+    string serialize(TreeNode* root) {
+        if(root == NULL) return "";
+        string s = "";
+        dfs(root, s);
+        return s;
+    }
+
+    // Decodes your encoded data to tree.
+    TreeNode* deserialize(string data) {
+        if(data == "") return NULL;
+        vector<int> nums = stringToVector(data);
+        
+        return createBST(nums, 0, nums.size() - 1);
+    }
+};
+
+// Your Codec object will be instantiated and called as such:
+// Codec* ser = new Codec();
+// Codec* deser = new Codec();
+// string tree = ser->serialize(root);
+// TreeNode* ans = deser->deserialize(tree);
+// return ans;