129.求根节点到叶节点数字之和.js

/*
 * @lc app=leetcode.cn id=129 lang=javascript
 *
 * [129] 求根节点到叶节点数字之和
 */

const { traverse } = require('@babel/core')

// @lc code=start
/**
 * 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
 * @return {number}
 */
var sumNumbers = function(root) {
  let sum = 0
  const path = []
  traverse(root)
  return sum

  function traverse(root) {
    if (!root) return
    path.push(root.val)
    if (!root.left && !root.right) {
      const pathSum = path.reduce(
        (accu, cur, i) => accu + cur * Math.pow(10, path.length - 1 - i),
        0
      )
      sum += pathSum
    }
    traverse(root.left)
    traverse(root.right)
    path.pop()
  }
}

// @lc code=end