Coding Interview Preparation Guide: DSA Study Plan

The handbook's 3-month plan (about 11 hours a week), three ways to order your study, and a 12-week table that points to the matching DSA lessons.

The four things interviewers score, techniques for before, during and after coding and when stuck, a mock-interview routine, a scoring sheet and a mistake log.

Input, output, constraints, examples and edge cases — and solving it by hand before writing any code.

How many times does the loop run? Reading time and space complexity from code, and from the constraints of a problem.

Counting with arrays and maps, how a hash table works inside, and why lookup becomes instant.

Pre-compute running totals so that any range sum is instant.

Two indices moving towards each other or in the same direction — pair sums, reversing, removing duplicates, 3Sum.

Reuse the last window's work instead of recomputing it.

Grow and shrink a window to find the longest or shortest answer.

The maximum subarray sum in a single pass, and the stock-trading problems built on the same idea.

Trading memory for speed with a map of what you have already met.

Anagrams, top frequencies, the majority element and grouping by a key.

Halve the search space every step; first and last positions; rotated arrays.

When the answer itself can be searched: square roots, eating speeds, shipping capacity.

Nodes and pointers (links to the next node), built from scratch.

Reverse a list, find the middle, and check if the list has a loop (a cycle).

Join sorted lists, find where a loop starts, and remove the nth node from the end.

Last in, first out. Examples: valid brackets, a stack that knows its minimum, and working out expressions.

First in, first out, and a queue you can use from both ends.

Find the next bigger item. It also solves temperatures, stock spans, histograms and rain water.

A function that calls itself, a base case that stops it, and the call stack underneath.

Draw every call as a tree, so recursion is easy to follow.

Pick or skip each item, to list every possible choice.

Choose, try, then undo. Examples: combination sum, N-Queens, word search.

Root, leaves and height. Preorder, inorder and postorder, drawn and coded.

Visit a tree one layer at a time with a queue.

Height, balance, diameter (the longest path) and path sums.

Build a priority queue by hand in JavaScript, then use it to find the top K items.

Vertices, edges and the adjacency list (each vertex's list of neighbours).

Count islands, flood fill, rotting oranges and copy a graph.

Put tasks in order when some depend on others, and find loops (cycles).

BFS when all steps cost the same, Dijkstra for other costs, and Bellman–Ford for limits.

Group things fast: connected groups, finding cycles and minimum spanning trees.

Repeated subproblems, memoisation, tabulation and saving memory.

House robber, coin change, decode ways, word break and the longest increasing subsequence.

Paths on a grid and the 0/1 knapsack problems.

Longest common subsequence, edit distance and the longest palindrome inside a string.

Prefix trees, and the bit tricks that interviews ask about.

Ask, plan, code, test: the 45 minutes, step by step.

A cheat sheet to spot patterns, a week-by-week plan and a checklist to test your memory.

A 45-minute routine, a take-home checklist and six full-stack tasks with tested code.

Behavioural answers, conflict stories, salary talks, offers and the first 90 days.

A one-page, scannable resume built from the Tech Interview Handbook guide: structure, strong bullets, ATS myths versus facts, and five before-and-after rewrites.