Algorithms & Data Structures

Active interview-preparation notes, implementations, and solved problems in Python.

I originally created this repository as a broad DSA reference. I am now using it as a structured interview-prep workspace: focusing on recurring problem-solving patterns, the reasoning behind them, complexity analysis, and clean implementations.

Active interview prep

Start here:

Interview Prep

Current focus:

• Arrays — complete
• Hash maps & sets — complete
• Two pointers — in progress
• Sliding window — next

The newer notes are organised around interview patterns rather than around isolated LeetCode problems.

Repository structure

interview-prep/
  README.md
  patterns/
    two-pointers.md

Practice Concepts/
  Data Structures/
  Trees/
  Graphs/
  Greedy Algorithms/
  Dynamic Programming/
  ...

Leetcode Problems/
  Easy/
  Medium/
  Hard/

archive/
  legacy-notes.md

Selected problems

A few useful examples already in the repository:

• Two Sum — hash map
• Two Sum II — two pointers
• Valid Palindrome
• LRU Cache
• Minimum Remove to Make Valid Parentheses

Study philosophy

For interview preparation I care about being able to explain:

1. what signal in the problem suggests a pattern;
2. what invariant/state the algorithm maintains;
3. why each decision is safe;
4. the time and space complexity;
5. the edge cases and common failure modes.

The aim is understanding and recall under interview conditions, not simply accumulating solved problems.

Historical notes

The repository's original long-form reference notes are preserved here:

Legacy DSA notes