LC: 255. Verify Preorder Sequence in Binary Search Tree

https://leetcode.com/problems/verify-preorder-sequence-in-binary-search-tree/

Question

255. Verify Preorder Sequence in Binary Search Tree

Given an array of unique integers preorder, return true if it is the correct preorder traversal sequence of a binary search tree.

Example 1:

Input: preorder = [5,2,1,3,6]
Output: true

Example 2:

Input: preorder = [5,2,6,1,3]
Output: false

Constraints:

• 1 <= preorder.length <= 104

• 1 <= preorder[i] <= 104

• All the elements of preorder are unique.

Follow up: Could you do it using only constant space complexity?

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