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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