STRINGS | Full DSA Guide + 5 LeetCode Problems in Python

A string is just letters in a row… exactly like a snake. 🐍 In this Big O Zoo episode, Sammy the Snake shows you what strings really are inside your computer: letters as numbers (ASCII, Unicode, UTF-8), how Python keeps s[i] at O(1), why strings are immutable, and the sneaky += trap that turns your code O(n²). Then we solve 5 of the most-asked string interview questions, step by step, in Python, plus a bonus. 🧩 Problems solved (Python) 1️⃣ Valid Anagram (LeetCode 242): Frequency counting 2️⃣ Valid Palindrome (LeetCode 125): Two pointers 3️⃣ Longest Substring Without Repeating Characters (LeetCode 3): Sliding window 4️⃣ Group Anagrams (LeetCode 49): Canonical key 5️⃣ Longest Palindromic Substring (LeetCode 5): Expand around center ⭐ Bonus: Reverse Words in a String (LeetCode 151) 📝 Homework: 387 · 680 · 424 · 647 👉 Watch the Arrays episode first. Strings are arrays of characters! 👉 Next enclosure: Linked Lists. #DSA #Strings #LeetCode #CodingInterview #Python #BigO #DataStructures #Algorithms