HASHING | Hash Tables Explained + 5 LeetCode Problems in Python

How can a Python dict find anything in O(1), no matter how much data you have? 🐦 In this Big O Zoo episode, Percy the Pigeon runs the zoo's post office and shows you exactly how hashing works: hash functions, buckets, collisions, chaining vs open addressing, load factor & resizing, hash flooding attacks, and what can (and can't) be a dictionary key. Then we solve 5 classic hashing interview problems step by step in Python, including building our own hash map from scratch, plus a bonus. 🧩 Problems solved (Python) 1️⃣ Contains Duplicate (LeetCode 217): Seen set 2️⃣ Design HashMap (LeetCode 706): Build it yourself 3️⃣ Longest Consecutive Sequence (LeetCode 128): Set lookups 4️⃣ Top K Frequent Elements (LeetCode 347): Count + bucket sort 5️⃣ Subarray Sum Equals K (LeetCode 560): Prefix sum + hash map ⭐ Bonus: Isomorphic Strings (LeetCode 205) 📝 Homework: 383 · 290 · 36 · 146 👉 Watch the Arrays & Strings episodes too: Two Sum and Group Anagrams were hashing all along! 👉 Next enclosure: Linked Lists. #DSA #Hashing #HashTable #LeetCode #CodingInterview #Python #BigO #DataStructures