/**
 * 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}
 */
const sortedArrayToBST = function (nums) {

};

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

/*
用数组的中间值作为根节点，然后递归的将左半部分和右半部分处理成一颗二叉搜索树，并设置成根节点的左右子树
*/
function f1(left, right, nums) {
  // 如果left > right, 说明这个区间没有元素，直接返回null
  if (left > right) return null;
  // 计算中间节点的索引
  const mid = left + Math.floor((right - left) / 2);

  // 创建根节点，或子树的根节点
  const root = new TreeNode(nums[mid]);
  // 递归处理左半部分和右半部分
  root.left = f1(left, mid - 1, nums);
  root.right = f1(mid + 1, right, nums);
  return root;
}