首发于 语雀文档@blueju

    代码：

    1. /**
    2.  * Definition for a binary tree node.
    3.  * class TreeNode {
    4.  *     val: number
    5.  *     left: TreeNode | null
    6.  *     right: TreeNode | null
    7.  *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
    8.  *         this.val = (val===undefined ? 0 : val)
    9.  *         this.left = (left===undefined ? null : left)
    10.  *         this.right = (right===undefined ? null : right)
    11.  *     }
    12.  * }
    13.  */
    15. function sortedArrayToBST(nums: number[]): TreeNode | null {
    16.     if (nums.length === 0) return null
    17.     const [middleIndex, middleValue] = getRoot(nums)
    18.     const tree = new TreeNode(middleValue)
    19.     tree.left = sortedArrayToBST(nums.slice(0, middleIndex))
    20.     tree.right = sortedArrayToBST(nums.slice(middleIndex + 1))
    21.     return tree
    22. };
    24. function getRoot(nums) {
    25.     const index = Math.floor(nums.length / 2)
    26.     return [index, nums[index]]
    27. }