0108.go

// Source: https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree
// Title: Convert Sorted Array to Binary Search Tree
// Difficulty: Easy
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.
//
// A height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.
//
// Example 1:
//
//   https://assets.leetcode.com/uploads/2021/02/18/btree1.jpg
//
//   Input: nums = [-10,-3,0,5,9]
//   Output: [0,-3,9,-10,null,5]
//   Explanation: [0,-10,5,null,-3,null,9] is also accepted:
//   https://assets.leetcode.com/uploads/2021/02/18/btree2.jpg
//
// Example 2:
//
//   https://assets.leetcode.com/uploads/2021/02/18/btree.jpg
//   Input: nums = [1,3]
//   Output: [3,1]
//   Explanation: [1,null,3] and [3,1] are both height-balanced BSTs.
//
// Constraints:
//
//   1 <= nums.length <= 10^4
//   -10^4 <= nums[i] <= 10^4
//   nums is sorted in a strictly increasing order.
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

type TreeNode struct {
	Val   int
	Left  *TreeNode
	Right *TreeNode
}

func sortedArrayToBST(nums []int) *TreeNode {
	l := len(nums)
	idx := l / 2

	if l == 0 {
		return nil
	}

	return &TreeNode{
		Val:   nums[idx],
		Left:  sortedArrayToBST(nums[:idx]),
		Right: sortedArrayToBST(nums[idx+1:]),
	}
}