【LeetCode热题100（42/100）】将有序数组转换为二叉搜索树

题目地址：链接

思路： 使用 二分思想 + 递归 构建儿茶搜索树

/**
 * 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}
 */
var sortedArrayToBST = function(nums) {
    let n = nums.length;
    function dfs(l, r) {
        let mid = (l + r) >> 1;
        let root = new TreeNode(nums[mid]);
        if(l <= mid - 1) root.left = dfs(l, mid - 1);
        if(mid + 1 <=  r) root.right = dfs(mid + 1, r);
        return root
    }
    let ans = dfs(0, nums.length - 1);
    return ans;
};