Yosgi Siqi Liu

Finding the path in a zigzag-labeled binary tree using the symmetry of each level's numbering.

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.

Summing root-to-leaf binary numbers with top-down pre-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.

Pruning subtrees that contain no 1 with post-order traversal, using a dummy parent so the root can also be pruned.

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

Computing the total tilt of a binary tree with recursion that returns each subtree's sum.

Finding the maximum path sum in a binary tree with recursion that returns each node's best downward contribution.