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### Grokking the Coding Interview: Patterns for Coding Questions

Master the coding interview by learning coding patterns. Act smartly, and follow the coding patterns.

Level:

Intermediate

Study Time:

61h

Lessons:

325

Playgrounds :

352

211,991 (Students)

Course Overview

Coding interviews are getting harder every day. A few years back, brushing up on key data structures and going through 50-75 coding interview questions was more than enough prep for an interview. Today, everyone has access to massive sets of coding problems, and they've gotten more difficult to account for that. 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 that, we've come up with a list of 20 patterns for coding questions, based on similarities in the techniques needed to solve them. As a result, once you're 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 in top companies including Google, Facebook, Amazon, and Microsoft.

Certification Included

Certification on completing the course.

Lifetime Access

Lifetime access including all future updates.

Course Content

• 24 Chapters • 325 Lessons

1.

Introduction

2 lessons

2.

Warmup

17 lessons

Why warmup?

Contains Duplicate (easy)

Solution: Contains Duplicate

Pangram (easy)

Solution: Pangram

Sqrt (easy)

Solution: Sqrt

Reverse Vowels (easy)

Solution: Reverse Vowels

Valid Palindrome (easy)

Solution: Valid Palindrome

Valid Anagram (easy)

Solution: Valid Anagram

Shortest Word Distance (easy)

Solution: Shortest Word Distance

Number of Good Pairs (easy)

Solution: Number of Good Pairs

3.

Pattern: Two Pointers

23 lessons

Introduction to Two Pointers Pattern

Pair with Target Sum (easy)

Solution: Pair with Target Sum

Remove Duplicates (easy)

Solution: Remove Duplicates

Squaring a Sorted Array (easy)

Solution: Squaring a Sorted Array

Triplet Sum to Zero (medium)

Solution: Triplet Sum to Zero

Triplet Sum Close to Target (medium)

Solution: Triplet Sum Close to Target

Triplets with Smaller Sum (medium)

Solution: Triplets with Smaller Sum

Subarrays with Product Less than a Target (medium)

Solution: Subarrays with Product Less than a Target

Dutch National Flag Problem (medium)

Solution: Dutch National Flag Problem

Problem Challenge 1: Quadruple Sum to Target (medium)

Solution: Problem Challenge 1: Quadruple Sum to Target

Problem Challenge 2: Comparing Strings containing Backspaces (medium)

Solution: Problem Challenge 2: Comparing Strings containing Backspaces

Problem Challenge 3: Minimum Window Sort (medium)

Solution: Problem Challenge 3: Minimum Window Sort

4.

Pattern: Island (Matrix Traversal) *NEW*

15 lessons

Introduction to Island Pattern

Number of Islands (easy)

Solution: Number of Islands

Biggest Island (easy)

Solution: Biggest Island

Flood Fill (easy)

Solution: Flood Fill

Number of Closed Islands (easy)

Solution: Number of Closed Islands

Problem Challenge 1

Solution: Problem Challenge 1

Problem Challenge 2

Solution: Problem Challenge 2

Problem Challenge 3

Solution: Problem Challenge 3

5.

Pattern: Fast & Slow Pointers

15 lessons

Introduction to Fast & Slow Pointers Pattern

LinkedList Cycle (easy)

Solution: LinkedList Cycle

Start of LinkedList Cycle (medium)

Solution: Start of LinkedList Cycle

Happy Number (medium)

Solution: Happy Number

Middle of the LinkedList (easy)

Solution: Middle of the LinkedList

Problem Challenge 1: Palindrome LinkedList (medium)

Solution: Problem Challenge 1: Palindrome LinkedList

Problem Challenge 2: Rearrange a LinkedList (medium)

Solution: Problem Challenge 2: Rearrange a LinkedList

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

Solution: Problem Challenge 3: Cycle in a Circular Array

6.

Pattern: Sliding Window

21 lessons

Introduction to Sliding Window Pattern

Maximum Sum Subarray of Size K (easy)

Solution: Maximum Sum Subarray of Size K

Smallest Subarray With a Greater Sum (easy)

Solution: Smallest Subarray With a Greater Sum

Longest Substring with K Distinct Characters (medium)

Solution: Longest Substring with K Distinct Characters

Fruits into Baskets (medium)

Solution: Fruits into Baskets

Longest Substring with Same Letters after Replacement (hard)

Solution: Longest Substring with Same Letters after Replacement

Longest Subarray with Ones after Replacement (hard)

Solution: Longest Subarray with Ones after Replacement

Problem Challenge 1: Permutation in a String (hard)

Solution: Problem Challenge 1: Permutation in a String

Problem Challenge 2: String Anagrams (hard

Solution: Problem Challenge 2: String Anagrams

Problem Challenge 3: Smallest Window containing Substring (hard)

Solution: Problem Challenge 3: Smallest Window containing Substring

Problem Challenge 4: Words Concatenation (hard)

Solution: Problem Challenge 4: Words Concatenation

7.

Pattern: Merge Intervals

15 lessons

Introduction to Merge Intervals Pattern

Merge Intervals (medium)

Solution: Merge Intervals

Insert Interval (medium)

Solution: Insert Interval

Intervals Intersection (medium)

Solution: Intervals Intersection

Conflicting Appointments (medium)

Solution: Conflicting Appointments

Problem Challenge 1: Minimum Meeting Rooms (hard)

Solution: Problem Challenge 1: Minimum Meeting Rooms

Problem Challenge 2: Maximum CPU Load (hard)

Solution: Problem Challenge 2: Maximum CPU Load

Problem Challenge 3: Employee Free Time (hard)

Solution: Problem Challenge 3: Employee Free Time

8.

Pattern: Cyclic Sort

17 lessons

Introduction to Cyclic Sort Pattern

Cyclic Sort (easy)

Solution: Cyclic Sort

Find the Missing Number (easy)

Solution: Find the Missing Number

Find all Missing Numbers (easy)

Solution: Find all Missing Numbers

Find the Duplicate Number (easy)

Solution: Find the Duplicate Number

Find all Duplicate Numbers (easy)

Solution: Find all Duplicate Numbers

Problem Challenge 1: Find the Corrupt Pair (easy)

Solution: Problem Challenge 1: Find the Corrupt Pair

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

Solution: Problem Challenge 2: Find the Smallest Missing Positive Number

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

Solution: Problem Challenge 3: Find the First K Missing Positive Numbers

9.

Pattern: In-place Reversal of a Linked List

11 lessons

Introduction to In-place Reversal of a Linked List Pattern

Reverse a LinkedList (easy)

Solution: Reverse a LinkedList

Reverse a Sub-list (medium)

Solution: Reverse a Sub-list

Reverse every K-element Sub-list (medium)

Solution: Reverse every K-element Sub-list

Problem Challenge 2: Rotate a LinkedList (medium)

Solution: Problem Challenge 2: Rotate a LinkedList

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

Solution: Problem Challenge 1: Reverse alternating K-element Sub-list

10.

Pattern: Tree Breadth First Search

19 lessons

Introduction to Tree Breadth First Search Pattern

Binary Tree Level Order Traversal (easy)

Solution: Binary Tree Level Order Traversal

Reverse Level Order Traversal (easy)

Solution: Reverse Level Order Traversal

Zigzag Traversal (medium)

Solution: Zigzag Traversal

Level Averages in a Binary Tree (easy)

Solution: Level Averages in a Binary Tree

Minimum Depth of a Binary Tree (easy)

Solution: Minimum Depth of a Binary Tree

Level Order Successor (easy)

Solution: Level Order Successor

Connect Level Order Siblings (medium)

Solution: Connect Level Order Siblings

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

Solution: Problem Challenge 1: Connect All Level Order Siblings

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

Solution: Problem Challenge 2: Right View of a Binary Tree

11.

Pattern: Tree Depth First Search

15 lessons

Introduction to Tree Depth First Search Pattern

Binary Tree Path Sum (easy)

Solution: Binary Tree Path Sum

All Paths for a Sum (medium)

Solution: All Paths for a Sum

Sum of Path Numbers (medium)

Solution: Sum of Path Numbers

Path With Given Sequence (medium)

Solution: Path With Given Sequence

Count Paths for a Sum (medium)

Solution: Count Paths for a Sum

Problem Challenge 1: Tree Diameter (medium)

Solution: Problem Challenge 1: Tree Diameter

Problem Challenge 2: Path with Maximum Sum (hard)

Solution: Problem Challenge 2: Path with Maximum Sum

12.

Pattern: Two Heaps

9 lessons

Introduction to Two Heaps Pattern

Find the Median of a Number Stream (medium)

Solution: Find the Median of a Number Stream

Sliding Window Median (hard)

Solution: Sliding Window Median

Maximize Capital (hard)

Solution: Maximize Capital

Problem Challenge 1: Next Interval (hard)

Solution: Problem Challenge 1: Next Interval

13.

Pattern: Subsets

19 lessons

Introduction to Subsets Pattern

Subsets (easy)

Solution: Subsets

Subsets With Duplicates (easy)

Solution: Subsets With Duplicates

Permutations (medium)

Solution: Permutations

String Permutations by changing case (medium)

Solution: String Permutations by changing case

Balanced Parentheses (hard)

Solution: Balanced Parentheses

Unique Generalized Abbreviations (hard)

Solution: Unique Generalized Abbreviations

Problem Challenge 1: Evaluate Expression (hard)

Solution: Problem Challenge 1: Evaluate Expression

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

Solution: Problem Challenge 2: Structurally Unique Binary Search Trees

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

Solution: Problem Challenge 3: Count of Structurally Unique Binary Search Trees

14.

Pattern: Modified Binary Search

21 lessons

Introduction to Modified Binary Search Pattern

Order-agnostic Binary Search (easy)

Solution: Order-agnostic Binary Search

Ceiling of a Number (medium)

Solution: Ceiling of a Number

Next Letter (medium)

Solution: Next Letter

Number Range (medium)

Solution: Number Range

Search in a Sorted Infinite Array (medium)

Solution: Search in a Sorted Infinite Array

Minimum Difference Element (medium)

Solution: Minimum Difference Element

Bitonic Array Maximum (easy)

Solution: Bitonic Array Maximum

Problem Challenge 1: Search Bitonic Array (medium)

Solution: Problem Challenge 1: Search Bitonic Array

Problem Challenge 2: Search in Rotated Array (medium)

Solution: Problem Challenge 2: Search in Rotated Array

Problem Challenge 3: Rotation Count (medium)

Solution: Problem Challenge 3: Rotation Count

15.

Pattern: Bitwise XOR

9 lessons

Introduction to Bitwise XOR Pattern

Single Number (easy)

Solution: Single Number

Two Single Numbers (medium)

Solution: Two Single Numbers

Complement of Base 10 Number (medium)

Solution: Complement of Base 10 Number

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

Solution: Problem Challenge 1: Flip and Invert an Image

16.

Pattern: Top 'K' Elements

29 lessons

Introduction to Top 'K' Elements Pattern

Top 'K' Numbers (easy)

Solution: Top 'K' Numbers

Kth Smallest Number (easy)

Solution: Kth Smallest Number

'K' Closest Points to the Origin (easy)

Solution: 'K' Closest Points to the Origin

Connect Ropes (easy)

Solution: Connect Ropes

Top 'K' Frequent Numbers (medium)

Solution: Top 'K' Frequent Numbers

Frequency Sort (medium)

Solution: Frequency Sort

Kth Largest Number in a Stream (medium)

Solution: Kth Largest Number in a Stream

'K' Closest Numbers (medium)

Solution: 'K' Closest Numbers

Maximum Distinct Elements (medium)

Solution: Maximum Distinct Elements

Sum of Elements (medium)

Solution: Sum of Elements

Rearrange String (hard)

Solution: Rearrange String

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

Solution: Problem Challenge 1: Rearrange String K Distance Apart

Problem Challenge 2: Scheduling Tasks (hard)

Solution: Problem Challenge 2: Scheduling Tasks

Problem Challenge 3: Frequency Stack (hard)

Solution: Problem Challenge 3: Frequency Stack

17.

Pattern: K-way Merge

11 lessons

Introduction to K-way Merge Pattern

Merge K Sorted Lists (medium)

Solution: Merge K Sorted Lists

Kth Smallest Number in M Sorted Lists (Medium)

Solution: Kth Smallest Number in M Sorted Lists

Kth Smallest Number in a Sorted Matrix (Hard)

Solution: Kth Smallest Number in a Sorted Matrix

Smallest Number Range (Hard)

Solution: Smallest Number Range

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

Solution: Problem Challenge 1: K Pairs with Largest Sum

18.

Pattern: Backtracking

11 lessons

Introduction to Backtracking Pattern

Combination Sum (medium)

Solution: Combination Sum

Word Search (medium)

Solution: Word Search

Sudoku Solver (hard)

Solution: Sudoku Solver

Factor Combinations (medium)

Solution: Factor Combinations

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

Solution: Split a String Into the Max Number of Unique Substrings

19.

Pattern: 0/1 Knapsack (Dynamic Programming)

13 lessons

Introduction to 0/1 Knapsack Pattern

0/1 Knapsack (medium)

Solution: 0/1 Knapsack

Equal Subset Sum Partition (medium)

Solution: Equal Subset Sum Partition

Subset Sum (medium)

Solution: Subset Sum

Minimum Subset Sum Difference (hard)

Solution: Minimum Subset Sum Difference

Problem Challenge 1: Count of Subset Sum (hard)

Solution: Problem Challenge 1: Count of Subset Sum

Problem Challenge 2: Target Sum (hard)

Solution: Problem Challenge 2: Target Sum

20.

Pattern: Topological Sort (Graph)

15 lessons

Introduction to Topological Sort Pattern

Topological Sort (medium)

Solution: Topological Sort

Tasks Scheduling (medium)

Solution: Tasks Scheduling

Tasks Scheduling Order (medium)

Solution: Tasks Scheduling Order

All Tasks Scheduling Orders (hard)

Solution: All Tasks Scheduling Orders

Alien Dictionary (hard)

Solution: Alien Dictionary

Problem Challenge 1: Reconstructing a Sequence (hard)

Solution: Problem Challenge 1: Reconstructing a Sequence

Problem Challenge 2: Minimum Height Trees (hard)

Solution: Problem Challenge 2: Minimum Height Trees

22.

Miscellaneous

2 lessons

24.

Conclusions

1 lesson