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Grokking the Coding Interview: Patterns for Coding Questions

Fast track your coding interview prep by learning coding patterns. Act smartly, and follow the coding patterns.

Level:

Intermediate

Study Time:

90h

Lessons:

543

Playgrounds :

617

Updated

Last month

4.6

(61,161 ratings)

183,255 learners

Course Overview

Coding interviews are becoming increasingly challenging. A few years back, brushing up on key data structures and going through 50 to 75 coding interview questions was more than enough prep for an interview. Today, everyone has access to massive sets of coding problems, and they have become more difficult to account for. The process has gotten more competitive. When our team sat together to brainstorm on ideas to make the interview process easier for candidates, we realized quickly that one skill helped us the most when we were preparing for coding interviews: "the ability to map a new problem to an already known problem." To help candidates with this, we have compiled a list of 33 common coding patterns to help solve coding questions. The idea is that once you are familiar with a pattern, you'll be able to solve dozens of problems with it. The techniques taught in this course have helped developers land jobs at top companies like Google, Meta, Amazon, Oracle, OpenAI, and Microsoft.

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Get instant access to all current and upcoming courses for one year.

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Certification on completing the course.

Gift for lifetime

Course Content

• Chapters • 543 Lessons

Introduction

2 lessons

Who Should Take This Course?

Course Overview

Warmup

17 lessons

Why warmup?

Contains Duplicate (easy)

Pangram (easy)

Reverse Vowels (easy)

Valid Palindrome (easy)

Valid Anagram (easy)

Shortest Word Distance (easy)

Number of Good Pairs (easy)

Sqrt (medium)

Pattern: Two Pointers

21 lessons

Introduction to Two Pointers Pattern

Pair with Target Sum (easy)

Find Non-Duplicate Number Instances (easy)

Squaring a Sorted Array (easy)

Triplet Sum to Zero (medium)

Triplet Sum Close to Target (medium)

Triplets with Smaller Sum (medium)

Dutch National Flag Problem (medium)

Problem Challenge 1: Quadruple Sum to Target (medium)

Problem Challenge 2: Comparing Strings containing Backspaces (medium)

Problem Challenge 3: Minimum Window Sort (medium)

Pattern: Fast & Slow Pointers

15 lessons

Introduction to Fast & Slow Pointers Pattern

LinkedList Cycle (easy)

Middle of the LinkedList (easy)

Start of LinkedList Cycle (medium)

Happy Number (medium)

Problem Challenge 1: Palindrome LinkedList (medium)

Problem Challenge 2: Rearrange a LinkedList (medium)

Problem Challenge 3: Cycle in a Circular Array (hard)

Pattern: Sliding Window

25 lessons

Introduction to Sliding Window Pattern

Maximum Sum Subarray of Size K (easy)

Smallest Subarray With a Greater Sum (easy)

Longest Substring with K Distinct Characters (medium)

Fruits into Baskets (medium)

Longest Substring with Same Letters after Replacement (hard)

Longest Subarray with Ones after Replacement (hard)

Problem Challenge 1: Permutation in a String (hard)

Problem Challenge 2: String Anagrams (hard)

Problem Challenge 3: Smallest Window containing Substring (hard)

Problem Challenge 4: Words Concatenation (hard)

Problem Challenge 5: Counting Subarrays with Product Less than a Target (hard)

Solution Problem Challenge 5: Counting Subarrays with Product Less than a Target

Problem Challenge 6: Subarrays with Product Less than a Target (hard)

Solution Problem Challenge 5: : Subarrays with Product Less than a Target

Pattern: Merge Intervals

15 lessons

Introduction to Merge Intervals Pattern

Merge Intervals (medium)

Insert Interval (medium)

Intervals Intersection (medium)

Conflicting Appointments (medium)

Problem Challenge 1: Minimum Meeting Rooms (hard)

Problem Challenge 2: Maximum CPU Load (hard)

Problem Challenge 3: Employee Free Time (hard)

Pattern: Cyclic Sort

17 lessons

Introduction to Cyclic Sort Pattern

Cyclic Sort (easy)

Find the Missing Number (easy)

Find all Missing Numbers (easy)

Find the Duplicate Number (easy)

Find all Duplicate Numbers (easy)

Problem Challenge 1: Find the Corrupt Pair (easy)

Problem Challenge 2: Find the Smallest Missing Positive Number (medium)

Problem Challenge 3: Find the First K Missing Positive Numbers (hard)

Pattern: In-place Reversal of a Linked List

11 lessons

Introduction to In-place Reversal of a Linked List Pattern

Reverse a LinkedList (easy)

Reverse a Sub-list (medium)

Reverse every K-element Sub-list (medium)

Problem Challenge 1: Reverse alternating K-element Sub-list (medium)

Problem Challenge 2: Rotate a LinkedList (medium)

Pattern: Stacks

16 lessons

Introduction to Stack

Implementing Stack Data Structure

Using Built-in Stack in Different Programming Languages

Applications of Stack

Problem 1: Balanced Parentheses (easy)

Problem 2: Reverse a String (easy)

Problem 3: Decimal to Binary Conversion (medium)

Problem 4: Next Greater Element (easy)

Problem 5: Sorting a Stack (easy)

Problem 6: Simplify Path (medium)

10.

Pattern: Monotonic Stack

15 lessons

Introduction to Monotonic Stack

Remove Nodes From Linked List (easy)

Remove All Adjacent Duplicates In String (easy)

Next Greater Element (easy)

Daily Temperatures (easy)

Remove All Adjacent Duplicates in String II (medium)

Sum of Subarray Minimums (medium)

Remove K Digits (hard)

11.

Pattern: Hash Maps

13 lessons

Introduction to Hash Tables

Hashing, Collisions, Overflow, and Resizing in Hashtables

Using Hashtable in Different Programming Languages

Problem 1: First Non-repeating Character (easy)

Problem 2: Largest Unique Number (easy)

Problem 3: Maximum Number of Balloons (easy)

Problem 4: Longest Palindrome(easy)

Problem 5: Ransom Note (easy)

12.

Level Order Traversal Pattern

New

15 lessons

Introduction to Level Order Traversal Pattern

Reverse Level Order Traversal (easy)

Find Largest Value in Each Tree Row (medium)

Maximum Width of Binary Tree (medium)

Maximum Level Sum of a Binary Tree (medium)

Zigzag Traversal (medium)

Even Odd Tree (medium)

N-ary Tree Level Order Traversal (hard)

13.

Pattern: Tree Breadth First Search

19 lessons

Introduction to Tree Breadth First Search Pattern

Binary Tree Level Order Traversal (easy)

Reverse Level Order Traversal (easy)

Zigzag Traversal (medium)

Level Averages in a Binary Tree (easy)

Minimum Depth of a Binary Tree (easy)

Level Order Successor (easy)

Connect Level Order Siblings (medium)

Problem Challenge 1: Connect All Level Order Siblings (medium)

Problem Challenge 2: Right View of a Binary Tree (easy)

14.

Pattern: Tree Depth First Search

15 lessons

Introduction to Tree Depth First Search Pattern

Binary Tree Path Sum (easy)

All Paths for a Sum (medium)

Sum of Path Numbers (medium)

Path With Given Sequence (medium)

Count Paths for a Sum (medium)

Problem Challenge 1: Tree Diameter (medium)

Problem Challenge 2: Path with Maximum Sum (hard)

15.

Pattern: Graphs

15 lessons

Introduction to Graph

Types of Graph

Graph Representations

Graph Traversal - Depth First Search(DFS)

Graph Traversal - Breadth First Search (BFS)

Find if Path Exists in Graph(easy)

Number of Provinces (medium)

Find Eventual Safe States (medium)

Minimum Number of Vertices to Reach All Nodes(medium)

Bus Routes (hard)

16.

Pattern: Island (Matrix Traversal)

15 lessons

Introduction to Island Pattern

Number of Islands (easy)

Biggest Island (easy)

Flood Fill (easy)

Number of Closed Islands (easy)

Problem Challenge 1 (easy)

Problem Challenge 2 (medium)

Problem Challenge 3 (medium)

17.

Pattern: Two Heaps

9 lessons

Introduction to Two Heaps Pattern

Find the Median of a Number Stream (medium)

Sliding Window Median (hard)

Maximize Capital (hard)

Problem Challenge 1: Next Interval (hard)

18.

Pattern: Subsets

19 lessons

Introduction to Subsets Pattern

Subsets (easy)

Subsets With Duplicates (easy)

Permutations (medium)

String Permutations by changing case (medium)

Balanced Parentheses (hard)

Unique Generalized Abbreviations (hard)

Problem Challenge 1: Evaluate Expression (hard)

Problem Challenge 2: Structurally Unique Binary Search Trees (hard)

Problem Challenge 3: Count of Structurally Unique Binary Search Trees (hard)

19.

Pattern: Modified Binary Search

21 lessons

Introduction to Modified Binary Search Pattern

Order-agnostic Binary Search (easy)

Ceiling of a Number (medium)

Next Letter (medium)

Number Range (medium)

Search in a Sorted Infinite Array (medium)

Minimum Difference Element (medium)

Bitonic Array Maximum (easy)

Problem Challenge 1: Search Bitonic Array (medium)

Problem Challenge 2: Search in Rotated Array (medium)

Problem Challenge 3: Rotation Count (medium)

20.

Pattern: Bitwise XOR

9 lessons

Introduction to Bitwise XOR Pattern

Single Number (easy)

Two Single Numbers (medium)

Complement of Base 10 Number (medium)

Problem Challenge 1: Flip and Invert an Image (hard)

21.

Pattern: Top 'K' Elements

29 lessons

Introduction to Top 'K' Elements Pattern

Top 'K' Numbers (easy)

Kth Smallest Number (easy)

'K' Closest Points to the Origin (easy)

Connect Ropes (easy)

Top 'K' Frequent Numbers (medium)

Frequency Sort (medium)

Kth Largest Number in a Stream (medium)

'K' Closest Numbers (medium)

Maximum Distinct Elements (medium)

Sum of Elements (medium)

Rearrange String (hard)

Problem Challenge 1: Rearrange String K Distance Apart (hard)

Problem Challenge 2: Scheduling Tasks (hard)

Problem Challenge 3: Frequency Stack (hard)

22.

Pattern: K-way Merge

11 lessons

Introduction to K-way Merge Pattern

Merge K Sorted Lists (medium)

Kth Smallest Number in M Sorted Lists (medium)

Kth Smallest Number in a Sorted Matrix (hard)

Smallest Number Range (hard)

Problem Challenge 1: K Pairs with Largest Sums (hard)

23.

Pattern: Greedy Algorithms

13 lessons

Introduction to Greedy Algorithm

Valid Palindrome II (easy)

Maximum Length of Pair Chain (medium)

Minimum Add to Make Parentheses Valid (medium)

Remove Duplicate Letters (medium)

Largest Palindromic Number (medium)

Removing Minimum and Maximum From Array (medium)

24.

Pattern: 0/1 Knapsack (Dynamic Programming)

14 lessons

What is Dynamic Programming?

Introduction to 0/1 Knapsack Pattern

0/1 Knapsack (medium)

Equal Subset Sum Partition (medium)

Subset Sum (medium)

Minimum Subset Sum Difference (hard)

Problem Challenge 1: Count of Subset Sum (hard)

Problem Challenge 2: Target Sum (hard)

25.

Fibonacci Numbers (Dynamic Programming)

New

12 lessons

Fibonacci numbers

Staircase

Number factors

Minimum jumps to reach the end

Minimum jumps with fee

House thief

26.

Palindromic Subsequence (Dynamic Programming)

New

10 lessons

Longest Palindromic Subsequence

Longest Palindromic Substring

Count of Palindromic Substrings

Minimum Deletions in a String to make it a Palindrome

Palindromic Partitioning

27.

Pattern: Backtracking

11 lessons

Introduction to Backtracking Pattern

Combination Sum (medium)

Word Search (medium)

Factor Combinations (medium)

Split a String Into the Max Number of Unique Substrings (medium)

Sudoku Solver (hard)

28.

Pattern: Trie

11 lessons

Introduction to Trie

Implement Trie (Prefix Tree) (medium)

Index Pairs of a String (easy)

Design Add and Search Words Data Structure (medium)

Extra Characters in a String (medium)

Search Suggestions System (medium)

29.

Pattern: Topological Sort (Graph)

15 lessons

Introduction to Topological Sort

Topological Sort (medium)

Tasks Scheduling (medium)

Tasks Scheduling Order (medium)

All Tasks Scheduling Orders (hard)

Alien Dictionary (hard)

Problem Challenge 1: Reconstructing a Sequence (hard)

Problem Challenge 2: Minimum Height Trees (hard)

30.

Pattern: Union Find

New

9 lessons

Introduction to Union Find Pattern

Redundant Connection (medium)

Number of Provinces (medium)

Is Graph Bipartite? (medium)

Path With Minimum Effort (medium)

31.

Pattern: Ordered Set

New

9 lessons

Introduction to Ordered Set Pattern

Merge Similar Items (easy)

132 Pattern (medium)

My Calendar I (medium)

Longest Continuous Subarray (medium)

32.

Pattern: Prefix Sum

New

15 lessons

Introduction Prefix Sum Pattern

Find the Middle Index in Array (easy)

Left and Right Sum Differences (easy)

Maximum Size Subarray Sum Equals k (medium)

Binary Subarrays With Sum (medium)

Subarray Sums Divisible by K (medium)

Sum of Absolute Differences in a Sorted Array (medium)

Subarray Sum Equals K (medium)

33.

Pattern: Multi-threaded

7 lessons

Introduction to Multi-threaded Pattern

Same Tree (medium)

Invert Binary Tree (medium)

Binary Search Tree Iterator (medium)

34.

Miscellaneous

2 lessons

Kth Smallest Number (hard)

35.

Revision

1 lessons

Coding Patterns: A Cheat Sheet

36.

Test Your Knowledge (Easy)

13 lessons

Introduction

Two Sum (easy)

Valid Perfect Square (easy)

Best Time to Buy and Sell (easy)

Valid Parentheses (easy)

Subtree of Another Tree (easy)

Design Parking System (easy)

37.

Test Your Knowledge (Medium)

52 lessons

Daily Temperatures (medium)

Group Anagrams (medium)

Decode String (medium)

Valid Sudoku (medium)

Product of Array Except Self (medium)

Maximum Product Subarray (medium)

Container With Most Water (medium)

Palindromic Substrings (medium)

Remove Nth Node From End of List (medium)

Find Minimum in Rotated Sorted Array (medium)

Pacific Atlantic Water Flow (medium)

Validate Binary Search Tree (medium)

Construct Binary Tree from Preorder and Inorder Traversal (medium)

Clone Graph (medium)

House Robber II (medium)

Decode Ways (medium)

Unique Paths (medium)

Word Break (medium)

Lowest Common Ancestor of a Binary Search Tree (medium)

Longest Consecutive Sequence (medium)

Meeting Rooms II (medium)

Encode and Decode Strings (medium)

Number of Connected Components in an Undirected Graph (medium)

Graph Valid Tree (medium)

Implement Trie (Prefix Tree) (medium)

Design Add and Search Words Data Structure (medium)

38.

Test Your Knowledge (Hard)

4 lessons

Longest Valid Parentheses (hard)

Serialize and Deserialize Binary Tree (hard)

39.

Conclusions

1 lessons

Where to Go from Here

What people say about our courses

Ashley Pean

Software Engineer

Check out Grokking the Coding Interview. Instead of trying out random Algos, they break down the patterns you need to solve them. Helps immensely with retention!

Simon Barker

Software Engineer

This is what I love about http://designgurus.io’s Grokking the coding interview course. They teach patterns rather than solutions.

Roger Cruz

Software Engineer

The world gets better inch by inch when you help someone else. If you haven't tried Grokking The Coding Interview, check it out, it's a great resource!

pikacodes

Software Engineer

I've tried every possible resource (Blind 75, Neetcode, YouTube, Cracking the Coding Interview, Udemy) and idk if it was just the right time or everything finally clicked but everything's been so easy to grasp recently with Grokking the Coding Interview!

Matzuk

Software Engineer

Algorithms can be daunting, but they're less so with the right guide. This course - https://www.designgurus.io/course/grokking-the-coding-interview, is a great starting point. It covers typical problems you might encounter in interviews.

Tonya Sims

Software Engineer

DesignGurus.io "Grokking the Coding Interview". One of the best resources I’ve found for learning the major patterns behind solving coding problems.

MO JAFRI

Software Engineer

The courses which have "grokking" before them, are exceptionally well put together! These courses magically condense 3 years of CS in short bite-size courses and lectures (I have tried Grokking System Design Interview, OODI, and Coding patterns). The Grokking courses are godsent, to be honest.

ABHISHEK GUPTA

Software Engineer

My offer from the top tech company would not have been possible without Grokking System Design. Many thanks!!

KAUSHIK JONNADULA

Software Engineer

Thanks for a great resource! You guys are a lifesaver. I struggled a lot in design interviews, and Grokking System Design gave me an organized process to handle a design problem. Please keep adding more questions.

About the Author

Meet Arslan Ahmad

The Expert Behind Grokking the Coding Interview

Design Gurus Founder

Ex-FAANG Manager

Industry Expertise & Leadership

Arslan Ahmad is the lead author of Grokking the Coding Interview, leveraging his extensive experience to craft a comprehensive technical interview course.

This expert-led program demystifies core data structures and algorithms for effective coding interview prep.

As a former software engineer at Facebook (Meta) and Microsoft, Arslan partnered with senior MAANG engineers (Google, Meta, Amazon, Microsoft, Uber) to ensure the course covers everything needed to excel in FAANG coding interviews.

This authoritative content distills proven coding interview strategies and patterns, offering expert guidance to help candidates master coding interviews with confidence.

500+

Interviews Conducted

10k+

Students Taught

Master advanced coding patterns for interviews: Unlock the key to acing MAANG-level coding questions.

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