intermediate~5h
Linked Lists and Trees Problem Set
A themed set of classic linked-list and binary-tree problems — reversing a list, Floyd's cycle detection, the middle-of-list two-pointer trick, BFS level-order traversal, BST validation, and lowest common ancestor — all built around pointer manipulation and the two-pointer/traversal techniques that make these structures tractable without extra memory.
Learning objectives
- Reverse a singly linked list iteratively by tracking three pointers (previous, current, next) through the list
- Detect a cycle in a linked list using Floyd's slow/fast pointer algorithm and explain why the pointers must eventually meet if a cycle exists
- Find the middle of a linked list in one pass using the slow/fast two-pointer technique
- Perform a level-order (breadth-first) traversal of a binary tree using a queue
- Validate whether a binary tree satisfies the binary search tree property using valid-range propagation, not just local parent/child comparisons
- Find the lowest common ancestor of two nodes in a binary search tree by using BST ordering to decide which direction to descend
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Linked Lists and Trees Problem Set