Completed Trees-1

[sreevardhan1099]

Trees-1
Problem 1
https://leetcode.com/problems/validate-binary-search-tree/

Problem 2
https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/

[super30admin]

Great job on both solutions! Your code is clean, efficient, and follows best practices.

For Problem-1.py (Validate BST):

• Your use of in-order traversal with a global prev variable is a classic and efficient approach. The conditional recursion to break early when the BST condition is violated is a nice touch that improves efficiency in worst-case scenarios.
• One minor suggestion: In Python, it's common to use None for comparisons rather than is not None. Your code already does this correctly, so keep it up.

For Problem-2.py (Construct Binary Tree from Preorder and Inorder Traversal):

• Your solution is well-optimized with the dictionary for O(1) lookups of indices in the inorder list. The recursive helper function is implemented correctly.
• You might consider adding error handling or checks for empty input, but the problem constraints assume non-empty trees, so it's not strictly necessary.

Both solutions demonstrate a strong understanding of tree traversals and recursion. Continue to write clear comments and maintain this level of code quality.