Posts tagged

Interviews

Bit Manipulation Tricks for Coding Interviews

A practical guide to the bitwise techniques that show up in coding interviews, starting with why interviewers love bit manipulation and a refresher on the six core operators (AND, OR, XOR, NOT, shifts). Covers six essential tricks with ASCII bit diagrams: checking and setting the k-th bit, clearing the lowest set bit with n & (n-1), XOR self-cancellation, power-of-two detection, swapping without a temp variable, and multiplying or dividing by powers of two with shifts. Then walks through five classic interview problems — single number, counting bits, missing number, power of two, and reversing bits — each with a worked Python solution and complexity analysis.

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Hash Maps and Sets: The Most Underrated FAANG Topic

Why hash maps and sets deserve more interview prep time than trees or dynamic programming. Explains the O(1) lookup superpower that turns quadratic brute-force solutions into linear ones, then covers the three patterns behind most hash map interview questions: frequency counting (valid anagram, top-K elements with Counter), the two-sum complement lookup family (two sum, subarray sum equals K with prefix sums), and grouping by canonical key (group anagrams with defaultdict). Includes five fully-solved Python problems, a pattern recognition cheat sheet, complexity analysis, and the follow-up questions interviewers ask about collisions and worst-case behavior.

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The Data Structures Cheatsheet: Time & Space Complexity for Every Structure You Need

A single-page reference covering the ten data structures that dominate coding interviews: arrays, linked lists, stacks, queues, hash maps, sets, trees, heaps, graphs, and tries. Each structure gets a complexity table with average and worst-case costs for access, search, insertion, and deletion, plus space complexity, a minimal Python snippet showing idiomatic usage, and guidance on when to reach for it. Includes a master comparison table for quick scanning before an interview and links to the full lessons in the 60-day challenge for deeper study.

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Tries Explained Simply (With Real Interview Problems)

A ground-up explanation of the trie (prefix tree) data structure aimed at coding interview preparation. Starts with an intuitive ASCII diagram showing how words share prefixes along root-to-node paths, then explains why tries beat hash sets for prefix queries with O(m) operations independent of dictionary size. Builds a complete, idiomatic Python Trie class with insert, search, and starts_with, analyzing time and space complexity along the way. Applies the structure to three classic interview problems — autocomplete (top-k suggestions per prefix), Word Search II on a 2D board with trie-guided backtracking and pruning, and Longest Word in Dictionary via BFS over complete words — each with a full worked solution.

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How Long Does It Take to Get a FAANG Offer?

A direct answer to how long FAANG interview preparation takes: 3-6 months of consistent study for most engineers, broken down by experience level. New grads with a CS degree typically need 2-4 months, self-taught developers 4-8 months, and experienced engineers who haven't touched algorithms recently 3-5 months. Includes a month-by-month preparation plan covering data structures, core patterns, timed practice, mock interviews, and system design, plus the three factors that most affect your personal timeline: starting skill, weekly study hours, and consistency.

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Backtracking Explained: N-Queens to Subsets

A complete guide to backtracking for coding interviews. Explains backtracking as constrained depth-first search over a decision tree, then introduces the universal choose/explore/unchoose template that solves nearly every backtracking interview problem. Works through four problem archetypes with full Python solutions: subsets (include/exclude decisions), permutations (ordering with a used-set), combination sum (reuse with pruning), and N-Queens (constraint satisfaction with column and diagonal tracking). Covers time complexity for each archetype, the classic mutable-list copy bug, and how to recognize a backtracking problem from its problem statement.

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