🔁 Day 8 of #90DaysOfDSA – A Day of Solid Revisions

Hey everyone! 👋
Today marks Day 8 of my #90DaysOfDSA challenge. Rather than tackling brand-new problems, I decided to take a step back and revise some key LeetCode classics that are frequently asked in interviews and fundamental to building strong problem-solving skills.

Revisiting problems isn’t just about redoing old work—it’s about recognizing patterns, refining logic, and deepening intuition. Here’s a breakdown of the problems I revised today:

---

🧩 1. Container With Most Water

🔹 Concept:

Given an array of heights, find the two lines that, along with the x-axis, form a container that holds the most water.

✅ Key Learning:

• Utilized the two-pointer approach.

• Moved the pointer with the shorter height to try and increase the area.

• Achieved O(n) time complexity.

🔧 Why This Matters:

This problem sharpens your ability to reason about greedy decisions and pointer movement—a pattern applicable in many array-based problems.

---

🧩 2. Longest Substring Without Repeating Characters (Revision)

🔹 Concept:

Find the length of the longest substring without repeating characters.

✅ Key Learning:

• Applied the sliding window technique.

• Used a hash set to track unique characters in the current window.

• Achieved O(n) complexity.

🔧 Why This Matters:

It's a perfect example of how to use sliding windows to efficiently track sequences while minimizing redundant checks.

---

🧩 3. Palindrome Check (Revision)

🔹 Concept:

Check if a given string is a palindrome, considering only alphanumeric characters and ignoring case.

✅ Key Learning:

• Cleaned the input using isalnum() and lower().

• Compared characters from both ends using two pointers.

🔧 Why This Matters:

This is a common question to test your understanding of string manipulation and pointer control in edge cases.

---

🧩 4. Two Sum (Revision)

🔹 Concept:

Find two numbers in an array that add up to a specific target.

✅ Key Learning:

• Used a hash map to store previously seen numbers and their indices.

• Got the solution in O(n) time complexity.

🔧 Why This Matters:

This is a must-know problem, not just for interviews but also as a gateway to hash-based lookups and map usage.

---

🧠 Final Thoughts

Today’s focus was on mastery, not novelty. By revisiting problems I’ve already solved, I:

• Reinforced key problem-solving patterns: two pointers, sliding window, and hashing.

• Sharpened my code clarity and reduced unnecessary logic.

• Gained confidence in my ability to handle foundational DSA problems under pressure.

📂 All Code: Day 8 GitHub Repo

---

🔜 What’s Next?

Tomorrow, I’ll resume tackling fresh problems. But today, I’m glad I took the time to slow down and solidify my base. DSA is not just about solving new problems—it’s about doing the basics better every day.

Let’s keep going! 💪

#90DaysOfDSA #DSA #Python #Leetcode #100DaysOfCode #TechJourney