Create 0450-delete-node-in-a-bst.cpp

Author: tahzeer

cpp/0450-delete-node-in-a-bst.cpp

@@ -0,0 +1,46 @@
+/**
+ * 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) {}
+ * };
+ */
+
+// Time: O(h)
+// Space: O(1)
+class Solution {
+public:
+    TreeNode* deleteNode(TreeNode* root, int key) {
+        if(root == nullptr) return root;
+
+        if(root->val > key) {
+            root->left = deleteNode(root->left, key);
+        }
+        else if(root->val < key) {
+            root->right = deleteNode(root->right, key);
+        }
+
+        // perform deletion if root->val == key
+        else {
+            if(!root->left) return root->right;
+            if(!root->right) return root->left;
+
+            // both left and right subtrees are not null
+            // traverse the right subtree to find the minimum/leftmost value
+            // (or) travel the left subtree to find the maximum/rightmost value
+            TreeNode* temp = root->right;
+            while(temp->left) {
+                temp = temp->left;
+            }
+            root->val = temp->val;
+
+            root->right = deleteNode(root->right, temp->val);
+        }
+
+        return root;
+    }
+};