Topics — Problem Mind-Maps

Each subdirectory is one LeetCode-style grouping (arrays-hashing, graphs, dp-1d, …). Inside every problems/ folder you get one markdown file per curated question, named NNN-kebab-title.md.

Concept layer vs problem layer

Topic index pages (e.g. Arrays & Hashing, Sliding Window) explain the idea and when it applies.
Pattern cards under Patterns are the recognition layer — cues, invariants, and recipes across companies.
Individual problem files add full mind-maps: variants, diagrams, solution stories, and senior interview framing.

If you are stuck on why a technique works, stay on the topic index or pattern page until the invariant clicks; only then drill the problem write-ups.

Suggested first pass (concepts before volume)

One possible order that builds dependencies clearly:

Arrays & Hashing — indexing, frequency, trade space for time.
Two Pointers and Sliding Window — linear scans with invariants.
Stack — deferred work and monotonic variants.
Linked List and Fast & Slow in Patterns — pointer discipline.
Binary Search — monotonic predicates and “search on answer”.
Trees, then graphs in the broader topic tree — BFS vs DFS tradeoffs.
Heap / Priority Queue — “next best” without full sorting.
Dynamic programming and graph topics as your map widens (see Roadmap).

You can deviate anytime; the goal is to reuse the same mental models instead of memorizing isolated tricks.

All topics

Topic	Focus
Advanced graphs	Weighted paths, Dijkstra, MST, advanced traversals
Arrays & hashing	Indexing, frequency maps, prefix tricks
Backtracking	Choice trees, pruning, state restore
Binary search	Monotonic predicates, search on answer
Bit manipulation	Masks, XOR, shifts, carry logic
DP (1D)	Linear state, tabulation, rolling variables
DP (2D)	Grid and sequence DP, path counting
Graphs	BFS, DFS, components, shortest paths
Greedy	Local choices with exchange arguments
Heap / priority queue	Top-k, scheduling, streaming order
Intervals	Overlap, merge, sweep-line reasoning
Linked list	Pointer rewiring, cycle detection
Math & geometry	GCD, primes, coordinates, formulas
Sliding window	Fixed and variable windows with invariants
Stack	Monotonic stacks, deferred work
System design coding	OOD-style coding interview problems
Trees	Traversals, BST rules, recursion returns
Tries	Prefix trees, autocomplete, word search
Two pointers	Sorted scans, opposite ends, partitioning

Layout

topics/<topic>/problems/NNN-title.md

Canonical duplicates

Some numbers appear in multiple rows of the Problem index; only one on-disk file exists:

Number	Canonical folder
152	Maximum Product Subarray (LeetCode 152)
121, 53, 7, …	See the index note — follow the path in the index, not a second copy.

Validation

From the repository root:

npm run docs:check-dsa

Checks DSA frontmatter and internal .md / .mdx links. After editing canonical source files under content/core-docs/dsa, run:

npm run docs:sync-dsa

This normalizes the source tree and syncs it to content/docs/dsa.