剑指OFFER----37、序列化二叉树(js实现)

题目

• 请实现两个函数，分别用来序列化和反序列化二叉树
• leetcode链接：https://leetcode-cn.com/problems/xu-lie-hua-er-cha-shu-lcof/

---

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */

/**
 * Encodes a tree to a single string.
 *
 * @param {TreeNode} root
 * @return {string}
 */
var serialize = function (root) {
  if (!root) return '[]'
  const queue = [root]
  const result = []
  while (queue.length) {
    const node = queue.shift()
    if (node) {
      result.push(node.val)
      queue.push(node.left)
      queue.push(node.right)
    } else {
      result.push(null)
    }
  }
  return JSON.stringify(result)
}

/**
 * Decodes your encoded data to tree.
 *
 * @param {string} data
 * @return {TreeNode}
 */
var deserialize = function (data) {
  if (data === '[]') return null
  const arr = JSON.parse(data)
  const root = new TreeNode(arr[0])
  const queue = [root]
  let i = 1
  while (queue.length) {
    const node = queue.shift()
    // 为0时也是可创建节点的，所以要判断是否为null
    if (arr[i] !== null) {
      node.left = new TreeNode(arr[i])
      queue.push(node.left)
    }
    i++
    if (arr[i] !== null) {
      node.right = new TreeNode(arr[i])
      queue.push(node.right)
    }
    i++
  }
  return root
}