0998-maximum-binary-tree-ii.js

/**
 * 998. Maximum Binary Tree II
 * https://leetcode.com/problems/maximum-binary-tree-ii/
 * Difficulty: Medium
 *
 * A maximum tree is a tree where every node has a value greater than any other value
 * in its subtree.
 *
 * You are given the root of a maximum binary tree and an integer val.
 *
 * Just as in the previous problem, the given tree was constructed from a list a
 * (root = Construct(a)) recursively with the following Construct(a) routine:
 * - If a is empty, return null.
 * - Otherwise, let a[i] be the largest element of a. Create a root node with the value a[i].
 * - The left child of root will be Construct([a[0], a[1], ..., a[i - 1]]).
 * - The right child of root will be Construct([a[i + 1], a[i + 2], ..., a[a.length - 1]]).
 * - Return root.
 *
 * Note that we were not given a directly, only a root node root = Construct(a).
 *
 * Suppose b is a copy of a with the value val appended to it. It is guaranteed that b has
 * unique values.
 *
 * Return Construct(b).
 */

/**
 * 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} val
 * @return {TreeNode}
 */
var insertIntoMaxTree = function(root, val) {
  if (!root || val > root.val) {
    const newRoot = createNode(val);
    newRoot.left = root;
    return newRoot;
  }

  root.right = insertIntoMaxTree(root.right, val);
  return root;

  function createNode(value) {
    return new TreeNode(value);
  }
};