Data Structures & Algorithms in Java
10 topics covering everything you need to pass coding interviews at top companies. Each topic has Java code examples, complexity analysis, and real interview questions.
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Beginner
Arrays
The most fundamental data structure. Understand indexing, traversal, and the two-pointer technique used in 90% of array interview problems.
Linked List
Master pointer manipulation, cycle detection, and reversal — interview favorites at every top company.
Stack
LIFO structure powering expression evaluation, backtracking, and monotonic stack problems.
Queue
FIFO structure essential for BFS, level-order traversal, and sliding window maximum.
Searching Algorithms
Binary search is not just for sorted arrays — master the template that solves dozens of "find the answer" problems.
Intermediate
Trees & Binary Search Trees
Hierarchical data structure at the heart of databases, file systems, and half of all interview problems.
Graphs
Model real-world networks — master BFS, DFS, topological sort, and shortest path algorithms.
Sorting Algorithms
From O(n²) basics to O(n log n) divide-and-conquer — understand the tradeoffs and when each algorithm wins.
Hashing
O(1) average lookups power two-sum, anagram detection, and frequency counting — the most commonly used data structure in interviews.