Create add_one_row_to_tree.cpp

Author: avidLearnerInProgress

add_one_row_to_tree.cpp

@@ -0,0 +1,40 @@
+/**
+ * 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 {
+public:
+    void addOneRowRecursive(TreeNode* root, int v, int depth, int current_depth) {
+        if(!root) return;
+        
+        if(current_depth == depth) { //breaking condition
+            TreeNode *subLeft = root->left; //store the current left
+            root->left = new TreeNode(v); //add new nodes with value = v at current_depth
+            root->left->left = subLeft; //attach previous left to left of new root->left
+            
+           TreeNode *subRight = root->right;
+            root->right = new TreeNode(v);
+            root->right->right = subRight;
+            return;
+        }
+        addOneRowRecursive(root->left, v, depth, current_depth + 1);
+        addOneRowRecursive(root->right, v, depth, current_depth + 1);
+    }
+    
+    TreeNode* addOneRow(TreeNode* root, int v, int d) {
+        if (d == 1) { //depth == 1, detach current root, add new root and add the older tree to the left of new root
+            TreeNode *newRoot = new TreeNode(v);
+            newRoot->left = root;
+            return newRoot;
+        }
+        addOneRowRecursive(root, v, d, 2);
+        return root;
+    }
+};