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

Author: aadil42

Diff for: javascript/0450-delete-node-in-a-bst.js

@@ -0,0 +1,40 @@
+/**
+ * Recursion
+ * h = height of the tree;
+ * Time O(h) | Space O(h)
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {number} key
+ * @return {TreeNode}
+ */
+var deleteNode = function(root, key) {
+    if(!root) return root;
+
+    if(key === root.val) {
+        if(!root.left) return root.right;
+        if(!root.right) return root.left;
+
+        // find the smallest val in right bst
+        let curr = root.right;
+        while(curr.left) {
+            curr = curr.left;
+        }
+        // change the curr value
+        root.val = curr.val;
+
+        root.right = deleteNode(root.right, root.val);
+    } else if(key < root.val) {
+        root.left = deleteNode(root.left, key);
+    } else {
+        root.right = deleteNode(root.right, key);
+    }
+
+    return root;
+};