108_convert-sorted-array-to-binary-search-tree.md

Problem

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

Example 1:

Given the sorted array: [-10,-3,0,5,9],

One possible answer is: [0,-3,9,-10,null,5], which represents the following height balanced BST:

      0
     / \
   -3   9
   /   /
 -10  5

Attempt

• Tree problems can usually be solved by recursive / iterative approach.
• Since the BST takes lower number to the left of a node & higher number to the right, the number on the middle should be the most parent node.

Recursive Solution

var sortedArrayToBST = function(nums) {
  //Corner case to break out of recursive calls
  if (!nums.length) return null
  //Declarations
  let n = nums.length
  let mid = Math.floor(nums.length / 2)
  let node = new TreeNode(nums[mid])
  //Recursive calls
  node.left = sortedArrayToBST(nums.slice(0, mid)) //tasks the lower value
  node.right = sortedArrayToBST(nums.slice(mid + 1)) //tasks the higher value
  return node
}

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Question Source - Leetcode