CodingPractice

Personal practice repo for coding interview prep — primarily LeetCode DSA (Python) and SQL.

Structure

.
├── LeetCode/DSA/   # Primary focus — Python solutions by pattern
├── SQL/            # LeetCode SQL + interview problems (TikTok, Google, Spotify, Twitter)
├── HackerRank/     # Secondary practice — algorithms by category
├── KQL/            # Kusto Query Language notebooks
└── Python/         # Codewars, InterviewQuery, misc Python implementations

LeetCode DSA

Solutions organized by algorithmic pattern:

• array-hashing/ — two pointers, sliding window, hashmap counting
• string/ — anagrams, palindromes, parsing
• linked_list/ — fast/slow pointers, reversal
• stack/ — monotonic stack, parentheses
• tree/ — DFS/BFS, recursion patterns
• graph/ — traversal, topological sort, shortest path
• heap/ — top-K, priority queue
• binary_search/ — search space reduction
• sorting/
• backtracking/ — subsets, combinations, permutations
• dynamic_programming/

Each file is self-contained with the Solution class and a test_*() function with LeetCode examples plus edge cases. Run directly with python3 path/to/problem.py.

SQL

LeetCode SQL problems (numbered files) and company interview questions (TikTok, Google, Spotify, Twitter, etc.). Topics covered:

• Window functions (RANK, DENSE_RANK, LAG/LEAD, running aggregates)
• Self-joins, anti-joins, correlated subqueries
• Date/time arithmetic, streaks, retention analysis
• Pivots, aggregation, percentile/median logic
• ETL data quality patterns

Conventions

• Python: 3.x, type hints (list[int], dict[str, int]), no typing.List
• File names: snake_case matching the problem slug
• Commit messages: the problem URL