1008. Construct Binary Search Tree from Preorder Traversal
Medium
30 Points
Array
Stack
Tree
Binary Search Tree
Monotonic Stack
Binary Tree
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 Node.val.
A preorder traversal of a binary tree displays the value of the node first, then traverses Node.left, then traverses Node.right.
Examples
Example 1
Input: preorder = [8,5,1,7,10,12]
Output: [8,5,10,1,7,null,12]
Example 2
Input: preorder = [1,3]
Output: [1,null,3]
Constraints
1 <= preorder.length <= 1001 <= preorder[i] <= 1000All the values of preorder are unique.
1008. Construct Binary Search Tree from Preorder Traversal
Medium
30 Points
Array
Stack
Tree
Binary Search Tree
Monotonic Stack
Binary Tree
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 Node.val.
A preorder traversal of a binary tree displays the value of the node first, then traverses Node.left, then traverses Node.right.
Examples
Example 1
Input: preorder = [8,5,1,7,10,12]
Output: [8,5,10,1,7,null,12]
Example 2
Input: preorder = [1,3]
Output: [1,null,3]
Constraints
1 <= preorder.length <= 1001 <= preorder[i] <= 1000All the values of preorder are unique.