Arrays & Hashing

Array Element Doubling

Array Filtering and Mapping

Array Manipulation

Array Min/Max Operations

Array Partition

Array Product of Next Two Elements

Array Sum

Array Transformation

Baby Names Search Engine - Exact Match

Best Value-for-Money Item

Board Game Jump (1-D Array)

Bus Departure Elapsed Time

Business Similarity (Jaccard Index)

Caesar Cipher

Calculate Amount Paid in Taxes

Can Place Flowers

Character Frequency

Check If a Word Occurs As a Prefix of Any Word in a Sentence

Check if All Characters Have Equal Number of Occurrences

Check if One String Swap Can Make Strings Equal

Check if the Sentence Is Pangram

Class Monitor Selection

Contains Duplicate

Cookie Handling Mechanism

Count Binary Substrings

Count Letter Occurrences Without Extra Space

Count Vowels in String

Counting Elements

Create Target Array in the Given Order

Data Integrity Checker

Date to Quarter Conversion

Degree of an Array

Distance Between Bus Stops

Divide Array Into Equal Pairs

Expanded String Generation

Fastest Lap

Filter Restaurants by Vegan-Friendly, Price and Distance

Find All Numbers Disappeared in an Array

Find Common Characters

Find Duplicate Words

Find Numbers with Even Number of Digits

Find Pivot Index

Find the Index of the First Occurrence in a String

Find Winner of an Election

Find Words That Can Be Formed by Characters

First Duplicate Element in Array

First Letter to Appear Twice

First Unique Character in a String

Frequency Count

Git Log Parser

High-Load Timestamps

Histogram of Characters

Implement docker ps Logic

Implement Map/Callback Function

Intersection of Two Arrays

IPv4 to IPv6 Conversion

Isomorphic Strings

Jewels and Stones

Last Hero Problem (F1 Race)

Latency Buckets Calculation

Leaders in an Array

Length of Last Word

License Key Formatting

Location Business Count

Log Parsing

Longest Continuous Increasing Subsequence

Longest Valid Password

Longest Word in String

Max Average Name-Value

Max Consecutive Ones

Maximum Number in List

Maximum Number of Balloons

Maximum Product of Three Numbers

Maximum Product of Two Elements in an Array

Median of Sorted List with Majority Element

Merge Sorted Array

Merge Two Maps with Summed Values

Minimum Index Sum of Two Lists

Mirror Characters of a String

Missing Ranges

Monotonic Array

Most Common Word

Most Frequent Character

Move Zeroes to End While Maintaining Order

N-Repeated Element in Size 2N Array

Name Statistics

Nano Slack - @Mentions

Normalized List Difference

Number of Good Pairs

Palindrome Permutation

Password Filtering

Plus One

Protocol Data Analyzer

Reverse an Array

Right Rotate String

Robot Return to Origin

Rotate String

Run Length Encoding

Sea Level Tracking

Second Largest Element in an Array

Service Health Monitor

Set Equality with Duplicates

Set Mismatch

Set Union and Intersection

Split Array into Odd Sum Pairs

String Character Count

String Error Count

String Number Summation

Sub-array Sum Condition

Summary Ranges

Total Tyres Calculation

Transaction Aggregator

Transaction Categorization

Transaction Grouping

Two Sum

Unique Email Addresses

Unique Number of Occurrences

URL Request Status Tracker

Valid Anagram

Valid Mountain Array

Valid Word

Verifying an Alien Dictionary

Vowel-Only Substrings

Weird Terminal Line Count

3D Trajectory Tokenization

3Sum Divisible by K

Alphanumeric Pattern Counter

Anomaly Detection in Procurement Transactions

Array Manipulation with Hash Maps

Array/Time/Grid Queries

Average Waiting Time

Award Top K Hotels

Binary String Flip and Count

Brick Wall

Bulb Switcher III

Bulls and Cows

Cache TTL Counter

Can Purchase Card

Card Parsing and Validation

Chat Filter

Circular Array Loop

Circular Character Roll Operation

Collision Detection (Linear Scan)

Consecutive Server Error Count

Consecutive Subarray

Consonant Shift Cipher

Continuous Subarray Sum

Convert Digits to Words

Convert String A to String B

Coordinate Distance Matching

Corporate Flight Bookings

Count Stable Subsegments

Count Unhappy Friends

Counterfeit Currency

CSV Transaction Parsing

Custom Array Map

Custom Array Methods - Map, Filter, Reduce

Data Formatter / Parser

Data Pivoting - Dictionary Parsing

Data Transformation Utility

Delete Two Elements to Preserve Mean

Detect Duplicates in Large Datasets

Determine if Two Strings Are Close

Dot Product of Two Sparse Vectors

Efficient Color Array Splitting

Email Scheduler / Subscription Rules

Encode and Decode Strings

Evaluate Word-Guess Feedback

Event Ingestion Stream Processing

Event Range Queries

Exchange Feed Optimization (Delta Updates)

Find Duplicate File in System

Find Element in Array (Partition Point)

Find Original Array From Doubled Array

Finding the Users Active Minutes

Fraction Equality Most Frequent

Fund Allocation & Daily Rebalancing

Gene Sequencing

Greedy Longest-Match Tokenizer

Grep With Context Lines

Group Anagrams

Group Isomorphic Words

Group Records by Key

Group Shifted Strings

High-Spending User Logic

Implement Memcpy

Interpolate Control Actions

Invalid Transactions

Inventory Combinations

IP and URL String Parsing

JavaScript Polyfills (Simulated in Python)

JSON Processing - Structured Record Creation

Jump Game with Wrap-Around

K-diff Pairs in an Array

Kth Largest Element in an Array

L33tsp3@k Bad Word Filter

Leader Detection

Letter Combinations of a Phone Number

Log File Customer Analysis

Log File IP Frequency

Log Stream Processing

Longest Consecutive Sequence

Longest Even Length Substring

Longest Subarray with Sum 0

Longest Well-Performing Interval

Loss Offsetting

Majority Element II

Making File Names Unique

Match Logs to Queries

Max Value after Updating Ranges

Maximize Distance to Closest Person

Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts

Maximum Concurrent Viewers

Maximum Consecutive Ones III

Maximum Embeddable Square Area

Maximum of Absolute Value Expression

Maximum Size Subarray Sum Equals k

Maximum Sum of Absolute Difference

Median of a Sorted Array

Median of Two Sorted Arrays

Merge Accounts with Common Emails

Merge Portfolio Timeseries

Message Merging and Sorting

MEX (Minimum Excluded Value)

Microservice Health Streak

Min Deletions to Avoid Overlap in First K

Minimum Area Rectangle

Minimum Moves to Match Arrays

Minimum Operations to Reduce Array to Zero

Monsters Battle

Mysterious Number Pairs

Next Closest Time

Next Permutation

Number of Matching Subsequences

Occurrence of Char in Subrange

Pairs of Songs With Total Durations Divisible by 60

Pancake Sorting

Parallel Database Query Auditor

Partition Array into Disjoint Intervals

Permutation Move-to-Front

Polynomial Multiplication

Prison Cells After N Days

Product Co-occurrence

Product of Array Except Self

Product Recommendation Engine

Range Coverage (Router Signal)

Range Sum Queries (Prefix Sums)

Range Sum Query - Immutable

Ransom Note

Remove Duplicates in a String

Remove One Element to Make the Array Strictly Increasing

Reorder Data in Log Files

Repeated DNA Sequences

Repeated String Match

Restore IP Addresses

Reverse Substring Match

Reverse Words at Odd Positions

Roll the String

Running Frequency Annotation

Search a 2D Matrix II

Search Function Optimization for Meeting History

Search Result Scoring

Second Largest Number in an Array

Second Most Frequent Tag

Sensor Anomaly Polling

Server Security Grouping

Shortest Uncommon Substring in an Array

Shortest Word Distance III

Similar Restaurant Names (K-Anagrams)

Slack Power Users

Snake Case to Camel Case (and vice versa)

Snakes and Ladders

Snowflake Uniqueness Check

Sparse Time: Code Stream Transformation

Split Array with Equal Sum

Streaming RLE and Bit-packed Codec

String Compression III

String Identity and Normalization

String Manipulation Without STL

String Presence at Large Scale

String Repetitions

Subarray Sum Equals K

Subarray Sums Divisible by K

Subarrays With LCM Equal to K

Subdomain Visit Count

Sum of Consecutive K

Sum of Even Numbers After Queries

Sum of Scores of Built Strings

Tail Command Implementation

Telemetry to JSON Parser

Test Score Stability Array Transformation

Text Word Distance

Tiered Discount Calculation

Time-Series Bucketing

Top K Frequent Elements

Top K Frequent Words

Transaction Balance & Rejection Logic

Transaction Logs (Process Logs)

Transaction Record: Add or Noticed

Twitter Space Active Time

Unique Morse Code Words

Unique Substrings

User Activity Logs

Valid Tic-Tac-Toe State

Valid Transaction Reference

Validate IP Address

Walking Robot Simulation

Weekly Aggregation

Zigzag Conversion

Count of Smaller Numbers After Self

Cycle Detection in Array

Find All Palindrome Pairs in Array of Strings

First Missing Positive

Function Signature Matcher (Method Dispatcher)

Guess the Word

K Empty Slots

Maximum Equal Frequency

Parallel Prefix Sum

Prefix Matching End Indices

Profitable Delivery Segments

Reconstruct Array from Subset Sums

Rule-based Marketplace Simulation

Shortest Palindrome

Sliding Window Maximum

Train Onboarding/Offboarding Range Query