Closest Binary Search Tree Value

Author: charlesbuczel

0270_closestBinarySearchTreeValue.js

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+/**
+ * @typedef {Object} TreeNode
+ * @description Definition for a binary tree node.
+ * @example
+ * 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 Root of a binary tree.
+ * @param {number} target Target value to find.
+ * @return {number} Value of a node closest to target
+ * @summary Closest Binary Search Tree Value {@link https://leetcode.com/problems/closest-binary-search-tree-value/}
+ * @description Given a binary tree and target, find node with closest value.
+ * Space O(1) - Constant number of variables created.
+ * Time O(h) - for height of the tree.
+ */
+const closestValue = (root, target) => {
+  let node = root;
+  closest = root.val;
+
+  while (node !== null) {
+    if (Math.abs(node.val - target) < Math.abs(closest - target)) closest = node.val;
+
+    node = target > node.val ? node.right : node.left;
+  }
+
+  return closest;
+};