Java (Micro)

Master the small Java code shapes that combine into full algorithms and data-structure solutions.

Values & Types

Program shape, a variable shelf, primitives, references, wrappers, and conversions.

Fixed arrays, dynamic lists, grids, indexed mutation, copying, and prefixes.

Lookup, defaults, counting, grouping, membership, and nested collections.

Branches, switch expressions, loop forms, two pointers, and sliding windows.

Signatures, arrays and lists at boundaries, lambdas, base cases, and memoization.

Object identity, bare trees, linked lists, tries, interfaces, and comparators.

ArrayDeque as a stack, conditional BFS queues, both deque ends, and monotonic queues.

Array and collection sorting, safe comparators, and binary-search bounds.

Separate min/max priority queues and disjoint sets with path compression.

Adjacency lists, BFS families, grid flood fill, DFS, and topological order.

Rolling states, memoized grids, snapshots, pruning, and undo steps.

Bit operations, wide arithmetic, Unicode-aware text, parsing, I/O, and exceptions.

Verify the compact Java syntax used by algorithm and data-structure solutions.