Coding Interview
102. Binary Tree Level Order Traversal
Jason Yang · 04 Aug, 2026
Binary Tree Level Order Traversal (LeetCode 102): the queue-based BFS, why snapshotting the queue size groups each level, and clean Java code.
Blog posts — page 9
Coding Interview
100. Same Tree
Jason Yang · 04 Aug, 2026
Same Tree (LeetCode 100): compare two binary trees for identical shape and values with a four-line recursion, plus the iterative queue version and its traps.
Coding Interview
98. Validate Binary Search Tree
Jason Yang · 04 Aug, 2026
Validate Binary Search Tree (LeetCode 98): why checking a node against its children fails, and the min/max bounds recursion that fixes it in Java.
Coding Interview
91. Decode Ways
Jason Yang · 04 Aug, 2026
Decode Ways (LeetCode 91): the Fibonacci-shaped count recurrence, why leading zeros kill a decoding, and the clean O(1)-space DP in Java.
Coding Interview
79. Word Search
Jason Yang · 04 Aug, 2026
Word Search (LeetCode 79): how DFS plus in-place marking walks the grid, why you restore each cell on the way out, and the clean Java backtracking solution.