LeetCode: Flip Binary Tree To Match Preorder Traversal Solution

1/**
2 * Definition for a binary tree node.
3 * function TreeNode(val, left, right) {
4 *     this.val = (val===undefined ? 0 : val)
5 *     this.left = (left===undefined ? null : left)
6 *     this.right = (right===undefined ? null : right)
7 * }
8 */
9/**
10 * @param {TreeNode} root
11 * @param {number[]} voyage
12 * @return {number[]}
13 */
14var flipMatchVoyage = function (root, voyage) {
15  const res = []
16  let pos = 0
17
18  const traverse = node => {
19    if (node === null) {
20      return true
21    }
22    if (node.val !== voyage[pos++]) {
23      return false
24    }
25    if (node.left !== null && node.left.val !== voyage[pos]) {
26      res.push(node.val)
27      return traverse(node.right) && traverse(node.left)
28    }
29    return traverse(node.left) && traverse(node.right)
30  }
31
32  return traverse(root) ? res : [-1]
33}