Data Structures and Algorithms : From 0 to HERO

Demonstrates finding all pairs x, y with x minus y equals k in an array, contrasting brute force O(n^2) with a sorting and binary search approach O(n log n).

Explore how hash tables map keys to values using a hash function, prevent duplicate keys, and replace values; examine the phone book analogy and digest-based password hashing in login.

Explore the queue data structure and its first-in, first-out behavior, learn enqueue and dequeue operations, and implement queues in Java using a linked list and the queue interface.

Explore how depth-first search traverses a graph from a start node, explores as far as possible, uses a visited array, and implements a recursive version.

Explore breadth-first search to traverse a graph from a starting node, visiting each neighbor and its children while marking visited nodes with a boolean array using a queue.

Count islands in a binary matrix using DFS to explore four-directional connected lands, handling edge cases and returning the total island count.