Yosgi Siqi Liu

AI will not replace software engineers as a whole. It will remove much of the repetitive, mechanical work and give engineers more leverage to focus on judgment, systems, users, and building better …

Deep-copying a linked list with random pointers using a hash map from old nodes to new.

Finding the smallest subtree containing all deepest nodes with a single bottom-up recursion that returns each subtree's depth.

Finding the minimum distance between BST nodes using the ordered property of in-order traversal.

Post-order traversal approach to delete target-valued leaf nodes using a dummy root.

Notes on counting good nodes in a binary tree using DFS with a running max.

Summing all root-to-leaf numbers with top-down pre-order DFS, carrying the running value down each path.

Counting nodes in a complete binary tree using left/right subtree depths instead of a full DFS.

Finding all nodes at distance K by first adding parent links with DFS, then searching outward from the target.

Deleting a node from a binary search tree by locating it via the BST property, then handling the three deletion cases.