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 <= 1041 <= preorder[i] <= 104- All the elements of
preorderare unique.
Follow up: Could you do it using only constant space complexity?