3 — Circular Linked List

Circular linked list structure — the tail-to-head wraparound, detecting 'the end' without a None sentinel, round-robin scheduling and circular buffers, the Josephus problem, and telling deliberate circularity apart from an accidental cycle bug.

3 — Two Pointers

Opposite-direction and same-direction pointer techniques for sorted arrays — Two Sum II, Container With Most Water, 3Sum, and in-place duplicate removal — plus how to tell the pattern apart from sliding window.

1 — Singly Linked List

Node-and-pointer structure, why there's no O(1) random access without contiguous memory, the head/tail/mid-list complexity trade-offs, and the reverse-a-list and find-the-middle worked examples every interview loop opens with.

Data Structures & Algorithms

A book-shaped table of contents for MAANG-interview DSA prep: Python language foundations, mathematical and algorithmic foundations, arrays/strings, linked structures, stacks/queues, trees, graphs, sorting/searching, dynamic programming, greedy algorithms, backtracking, bit manipulation, advanced data structures, advanced algorithms, interview problem patterns, and MAANG interview mastery — a book-length progression from fundamentals to Google/Meta/Amazon/Apple/Netflix/Microsoft (L4–L6) interview readiness.

1 — Two Pointers Pattern

Recognizing when a problem's brute-force nested loop collapses to a single pass with two coordinated pointers.

10 — BFS Pattern

Recognizing shortest-path/level-order/minimum-step problems that breadth-first search solves optimally on unweighted graphs.

11 — Tree DFS Pattern

Recognizing tree problems that reduce to a DFS template carrying a small amount of state root-to-leaf.

12 — Graph Pattern

Recognizing problems phrased as text/grid/relationship data that are actually graph traversal or connectivity in disguise.