Leetcode Problem 255. Verify Preorder Sequence in Binary Search Tree

255. Verify Preorder Sequence in Binary Search Tree

Leetcode Solutions

Approach: Monotonic Stack

  1. Initialize minLimit to negative infinity and an empty stack.
  2. Iterate over each num in preorder:
    • While the stack is not empty and the top of the stack is less than num, pop from the stack and update minLimit.
    • If num is less than or equal to minLimit, return false.
    • Push num onto the stack.
  3. If the entire preorder is processed without returning false, return true.
UML Thumbnail

Approach: Constant Auxiliary Space

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