Tree and Graph Traversal Questions

Comprehensive mastery of tree and graph traversal algorithms, representations, and common interview problem patterns. Understand graph models and representation choices including adjacency lists versus adjacency matrices and trade offs based on sparsity and density, as well as properties such as directed versus undirected and weighted versus unweighted edges. Know visited state management to avoid cycles and techniques for cycle detection. Implement breadth first search and depth first search in both recursive and iterative forms, understand when to use a queue versus a stack, and analyze time and space complexity. Apply traversals to problems such as shortest path in unweighted graphs, connected component detection, topological sort for dependency ordering, cycle detection, path existence, and island counting. For trees, master traversal orders including in order, pre order, post order, and level order with both recursive and iterative implementations, including explicit stack based approaches and constant space approaches where relevant. Practice tree specific problems such as lowest common ancestor, path sum, tree serialization and deserialization, validating binary search trees, balancing and reconstruction of trees from traversal sequences, and converting between tree and graph formulations. Emphasize clean code, correctness, handling edge cases such as empty or skewed structures, recursion base cases and depth limits, and explaining trade offs between recursion and iterative solutions with respect to performance and memory.