16 lessons

Crack the Interview — 15 Algorithmic Patterns

stop memorizing solutions — start recognizing the patterns underneath. 15 algorithmic patterns, each with real problems of increasing difficulty, solutions in Go, Rust, and C, and the kind of complexity analysis and edge-case awareness that interviewers are actually looking for.

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Crack the Interview — 15 Algorithmic Patterns

Introduction

01
How to Think in Patterns
free
how to recognize which pattern fits a problem, structure your interview answers clearly, and why Go is an effective language for coding interviews

Two Pointers

02
Two Pointers
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how to use converging pointers on sorted data to solve pair-sum, container problems, and in-place deduplication without extra space

Sliding Window

03
Sliding Window
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how to apply fixed and variable-width windows to find maximum subarray sums, longest substrings without repeats, and minimum window substrings

Fast & Slow Pointers

04
Fast & Slow Pointers
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how to detect cycles with Floyd's algorithm, find cycle start points, and locate the middle of a linked list without extra space

Merge Intervals

05
Merge Intervals
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how to merge overlapping intervals with sort-then-sweep, insert into existing intervals, and solve scheduling problems like meeting rooms

Cyclic Sort

06
Cyclic Sort
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how to exploit the value-to-index mapping to find missing numbers, duplicates, and first missing positive in O(n) time with O(1) space

In-Place Linked List Reversal

07
In-Place Linked List Reversal
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how to reverse linked list pointers in-place, handle sub-list reversals, and implement reverse-every-K-group without extra space

Tree BFS

08
Tree BFS
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how to solve level-order tree problems including zigzag traversal, right side view, minimum depth, and level averages

Tree DFS

09
Tree DFS
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how to solve recursive tree problems like path sum, max path sum, tree diameter, and serialization by choosing the right traversal order

Two Heaps

10
Two Heaps
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how to pair a min-heap and max-heap to compute streaming medians, handle sliding window medians, and solve capital allocation problems

Subsets & Backtracking

11
Subsets & Backtracking
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how to generate subsets, permutations, and combinations using backtracking, prune invalid branches early, and handle duplicates correctly

Modified Binary Search

12
Modified Binary Search
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how to apply binary search to non-obvious inputs like rotated arrays, sorted matrices, peak elements, and bitonic sequences

Bitwise XOR

13
Bitwise XOR
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how to use XOR's self-cancellation property to find single numbers, isolate pairs of unique elements, and solve complement problems in O(n) time

Top K Elements

14
Top K Elements
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how to use a heap for efficient selection of kth largest elements, top K frequent items, K closest points, and string reorganization

K-Way Merge

15
K-Way Merge
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how to merge K sorted sources using a min-heap, find kth smallest in a sorted matrix, and compute the smallest range covering elements from K lists

Topological Sort

16
Topological Sort
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how to order tasks with dependencies using topological sort, solve course prerequisites and alien dictionary, and generate all valid orderings

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