# LeetPrep

> Coding interview prep: DSA, LeetCode patterns and system design


## Posts

- [How to Approach a System Design Interview: URL Shortener Example](https://leetprep.online/system-design-interview-approach-url-shortener/): A repeatable framework for system design interviews, applied to designing a URL shortener with simple capacity estimates.
- [A 30-Day Coding Interview Study Plan That Actually Works](https://leetprep.online/coding-interview-study-plan-30-days/): A realistic four-week plan for coding interview preparation, with daily habits, topic order and how to review your mistakes.
- [Dynamic Programming for Beginners: Climbing Stairs and Coin Change](https://leetprep.online/dynamic-programming-for-beginners/): A gentle introduction to dynamic programming: recursion, memoization and tabulation on two classic interview problems.
- [Tree Traversals in Python: DFS, BFS and Grid Problems](https://leetprep.online/tree-traversals-dfs-bfs-python/): Understand inorder DFS, level-order BFS and how the same ideas solve Number of Islands on a grid.
- [Binary Search: A Reliable Template and the Mistakes to Avoid](https://leetprep.online/binary-search-template-common-mistakes/): A simple binary search template, a lower-bound variant and the search-on-answer trick, with the off-by-one mistakes that cause most bugs.
- [Sliding Window Pattern Explained with Python Examples](https://leetprep.online/sliding-window-pattern-explained/): Learn the fixed and variable sliding window techniques with two worked problems and a template you can reuse.
- [Two Sum: From Brute Force to Hash Map](https://leetprep.online/two-sum-brute-force-to-hash-map/): Solve LeetCode Two Sum step by step, from the obvious O(n squared) loop to a one-pass hash map solution in O(n).

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