108.将有序数组转换为二叉搜索树.js

/*
 * @lc app=leetcode.cn id=108 lang=javascript
 *
 * [108] 将有序数组转换为二叉搜索树
 */

// @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 {number[]} nums
 * @return {TreeNode}
 */
// TODO
var sortedArrayToBST = function(nums) {
  return build(nums, 0, nums.length - 1)

  function build(nums, lo, hi) {
    if (lo > hi) {
      return null
    }
    // const mid = Math.floor((lo + hi) / 2)
    const mid = lo + parseInt((hi - lo) / 2) // ❗
    const root = new TreeNode(nums[mid])
    root.left = build(nums, lo, mid - 1)
    root.right = build(nums, mid + 1, hi)
    return root
  }
}

function TreeNode(val, left, right) {
  this.val = val === undefined ? 0 : val
  this.left = left === undefined ? null : left
  this.right = right === undefined ? null : right
}

console.log(
  'sortedArrayToBST([-10,-3,0,5,9])',
  sortedArrayToBST([-10, -3, 0, 5, 9])
)

// @lc code=end