Blog posts — page 6

Coding Interview

Jason Yang · 04 Aug, 2026

Word Search II (LeetCode 212): why one shared Trie beats running Word Search once per word, plus the backtracking DFS and pruning tricks, in Java.

Coding Interview

Jason Yang · 04 Aug, 2026

Design Add and Search Words (LeetCode 211): store words in a trie, then DFS through it so a '.' wildcard can branch into every child. Java solution explained.

Coding Interview

Jason Yang · 04 Aug, 2026

Implement Trie (LeetCode 208): build a prefix tree in Java where each node branches 26 ways, so insert, search, and startsWith all run in O(word length).

Coding Interview

Jason Yang · 04 Aug, 2026

Course Schedule (LeetCode 207): the whole problem is 'does this directed graph have a cycle?' Solve it with Kahn's topological sort in Java, plus the DFS alternative.

Coding Interview

Jason Yang · 04 Aug, 2026

Reverse Linked List (LeetCode 206): the three-pointer flip that reverses a singly linked list in place, plus the recursive version and why order matters.