Given an array of integers preorder, which represents the preorder traversal of a BST (i.e., binary search tree), construct the tree and return its root.
It is guaranteed that there is always possible to find a binary search tree with the given requirements for the given test cases.
A binary search tree is a binary tree where for every node, any descendant of
Node.left has a value strictly less than
Node.val, and any descendant of
Node.right has a value strictly greater than
A preorder traversal of a binary tree displays the value of the node first, then traverses
Node.left, then traverses
Input: preorder = [8,5,1,7,10,12] Output: [8,5,10,1,7,null,12]
Input: preorder = [1,3] Output: [1,null,3]
1 <= preorder.length <= 100
1 <= preorder[i] <= 108