Coding Interview
271. Encode and Decode Strings
Jason Yang · 04 Aug, 2026
Encode and Decode Strings (LeetCode 271): why a delimiter alone can't work, and the length-prefix codec that round-trips any characters in Java.
Blog posts — page 4
Coding Interview
269. Alien Dictionary
Jason Yang · 04 Aug, 2026
Alien Dictionary (LeetCode 269): turn a sorted word list into a character graph, then topologically sort it with Kahn's BFS in Java — cycles and prefixes included.
Coding Interview
268. Missing Number
Jason Yang · 04 Aug, 2026
Missing Number (LeetCode 268): why XOR-ing every index with every value leaves exactly the missing one, plus the Gauss-sum alternative, in Java.
Coding Interview
261. Graph Valid Tree
Jason Yang · 04 Aug, 2026
Graph Valid Tree (LeetCode 261): a tree is a connected, acyclic graph with exactly n-1 edges — solve it with union-find cycle detection in Java.
Coding Interview
253. Meeting Rooms II
Jason Yang · 04 Aug, 2026
Meeting Rooms II (LeetCode 253): find the minimum rooms by tracking peak overlap — the min-heap solution and the sweep-line trick, both in Java.