Archives

All the articles I've archived.

2025 ¹⁶

March ³

System Design - How do Websockets Work
Published:Mar 15, 2025 at 06:23 AM
How do websockets work comparing to http?
LeetCode 658 LintCode 460 Find K Closest Elements
Published:Mar 24, 2025 at 06:23 AM
Solutions for LeetCode 658 LintCode 460, medium, tags: array, binary-search, sliding-window, sorting, heap; companies: google.
LeetCode 2539 LintCode 3855 Count the Number of Good Subsequences
Published:Mar 21, 2025 at 06:23 AM
Solutions for LeetCode 2539 LintCode 3855, hard, tags: enumerate, string, hash table, math, combinatorics, counting.

February ¹

LeetCode 2450 LintCode 3841 Number of Distinct Binary Strings After Applying Operations
Updated:Feb 22, 2025 at 06:23 AM
Solutions for LeetCode 2450 LintCode 3841, medium, tags: math, string.

January ¹²

System Design - Event Loop for Concurrent Applications
Published:Jan 6, 2025 at 06:23 AM
event loop system design pattern/construct event loop (message dispatcher), reactor/actor pattern, non-blocking mechanism for concurrent applications
HackerRank and GeeksForGeeks Minimum Replacements/Substitutions to Make Adjacent Characters Unequal
Published:Jan 2, 2025 at 06:23 AM
Solutions for , easy, tags: array, sliding window; companies: salesforce.
How could we interview job candidates to find the right teammates? Why should we care?
Updated:Jan 23, 2025 at 10:12 AM
how should we interview other job candidates to find the teammates we like? tips and suggestions on how to interview teammate or junior engineers.
LeetCode 206 LintCode 35 Reverse Linked List
Published:Jan 30, 2025 at 06:23 AM
Solutions for LeetCode 206 LintCode 35, easy, tags: linked list, recursion; companies: bytedance.
LeetCode 532 LintCode 1187 K-diff Pairs in An Array
Published:Jan 17, 2025 at 06:23 AM
Solutions for LeetCode 532 LintCode 1187, medium, tags: array, hash table, counting, two-pointers, binary-search; companies: nvidia, amazon.
LeetCode 916 LintCode 1726 Word Subsets
Published:Jan 8, 2025 at 06:23 AM
Solutions for LeetCode 916 LintCode 1726, medium, tags: array, hash table, string.
LeetCode 1166 LintCode 3677 Design File System
Published:Jan 28, 2025 at 06:23 AM
Solutions for LeetCode 1166 LintCode 3677, medium, tags: hash table, trie, string, design.
LeetCode 1400 Construct K Palindrome Strings
Published:Jan 9, 2025 at 06:23 AM
Solutions for LeetCode 1400, medium, tags: hash table, string, greedy, counting.
LeetCode 1930 Unique Length-3 Palindromic Subsequences
Published:Jan 5, 2025 at 06:23 AM
Solutions for LeetCode 1930, medium, tags: hash table, string, bit manipulation, prefix sum.
LeetCode 2017 Grid Game
Published:Jan 20, 2025 at 06:23 AM
Solutions for LeetCode 2017, medium, tags: array, prefix sum, dynamic programming, matrix.
LeetCode 542 LintCode 974 01 Matrix and LeetCode 1765 Map of Highest Peak
Published:Jan 19, 2025 at 06:23 AM
Solutions for LeetCode 542, LeetCode 1765, and LintCode 974, hard, tags: array, queue, sliding window, heap, monotonic queue.
LeetCode Meeting Rooms Derivative Question
Published:Jan 10, 2025 at 06:23 AM
Solutions for meeting rooms derivative question, hard, tags: heap, line sweep, ordered map; companies: salesforce.

2024 ⁷⁶

December ³⁰

Generative AI (Artificial Intelligence) with Large Language Models (LLM) - Part 1
Updated:Dec 14, 2024 at 10:12 AM
generative AI (artificial intelligence) machine learning with large language models
AWS (Amazon Web Services) Tips and Cheatsheet
Updated:Dec 7, 2024 at 10:12 AM
tips for using AWS
How to Draw Circles and Arcs with Python Library Matplotlib
Updated:Dec 5, 2024 at 10:12 AM
tips for matplotlib python draw arcs, robot walks, project euler 208
How to Install SortedContainers in the Python Shell or With a Python Script
Updated:Dec 1, 2024 at 10:12 AM
tips for installing sortedcontainers in a python shell
Java CheatSheet
Updated:Dec 26, 2024 at 10:12 AM
tips for using java
Linux Cheatsheet, tips and Commands
Updated:Dec 4, 2024 at 10:12 AM
tips for linux commands and tips
HackerRank GET Requests for GIF Images
Published:Dec 8, 2024 at 06:23 AM
Solutions for hacker rank get requests for gif images, medium, tags: file, hash set.
HackerRank Programmer Strings
Published:Dec 29, 2024 at 06:23 AM
Solutions for HackerRank Programmer Strings, hard, tags: string, hash table.
HackerRank Robot Walks and Project Euler 208 Solutions
Published:Dec 3, 2024 at 06:23 AM
Solutions for project euler 208 and hackerrank question robot walks, hard, tags: math, simulation.
LeetCode 1 LintCode 56 Two Sum
Published:Dec 4, 2024 at 06:23 AM
Solutions for LeetCode 1 LintCode 56, easy, tags: array, hash table.
LeetCode 53 LintCode 41 Maximum Subarray
Published:Dec 1, 2024 at 08:23 AM
Solutions for LeetCode 53 and LintCode 41, medium, tags: array, divide and conquer, dynamic programming, prefix sum, companies: ltk.
LeetCode 339 LintCode 551 Nested List Weight Sum
Published:Dec 15, 2024 at 07:23 AM
Solutions for LeetCode 339 LintCode 551, medium, tags: dfs, bfs; companies: salesforce.
LeetCode 520 LintCode 1202 IPO
Published:Dec 12, 2024 at 06:23 AM
Solutions for LeetCode 520 LintCode 1202, hard, tags: array, heap, greedy, sorting, binary search, dynamic programming, quick select.
LeetCode 540 LintCode 1183 Single Element in a Sorted Array
Published:Dec 5, 2024 at 06:23 AM
Solutions for LeetCode 540 LintCode 1183, medium, tags: array, binary search.
LeetCode 691 LintCode 1081 Stickers to Spell Word
Published:Dec 17, 2024 at 06:23 AM
Solutions for LeetCode 239, hard, tags: array, queue, sliding window, heap, monotonic queue.
LeetCode 713 LintCode 1075 Subarray Product Less Than K
Published:Dec 10, 2024 at 06:23 AM
Solutions for LeetCode 713 and LintCode 1075, medium, tags: sliding window, two pointers, prefix sum; companies: salesforce, yatra.
LeetCode 875 LintCode 1492 Koko Eating Bananas
Published:Dec 24, 2024 at 06:23 AM
Solutions for LeetCode 875 LintCode 1492, medium, tags: array, binary search; companies: facebook, salesforce.
LeetCode 994 LintCode 3726 Rotting Oranges
Published:Dec 13, 2024 at 06:23 AM
Solutions for LeetCode 994 LintCode 3726, medium, tags: graph, bfs, array; companies: tiktok.
LeetCode 1422 Maximum Score After Splitting a String
Published:Dec 30, 2024 at 06:23 AM
Solutions for LeetCode 1422, easy, tags: string, prefix sum.
LeetCode 1650 LintCode 474 Lowest Common Ancestor of a Binary Tree III
Published:Dec 9, 2024 at 07:23 AM
Solutions for LeetCode 1650 LintCode 474, medium, tags: binary tree, hash table, two pointers; companies: microsoft.
LeetCode 2415 Reverse Odd Levels of Binary Tree
Published:Dec 18, 2024 at 06:23 AM
Solutions for LeetCode 239, hard, tags: array, queue, sliding window, heap, monotonic queue.
LeetCode 2466 LintCode 3854 Count Ways to Build Good Strings (Number of Good Binary Strings)
Published:Dec 28, 2024 at 06:23 AM
Solutions for LeetCode 2466 LintCode 3854, medium, tags: array, dynamic programming.
LeetCode 2558 Take Gifts From the Richest Pile
Published:Dec 11, 2024 at 06:23 AM
Solutions for LeetCode 2558, easy, tags: array, heap, simulation.
LeetCode 2559 Count Vowel Strings in Ranges
Published:Dec 31, 2024 at 06:23 AM
Solutions for LeetCode 2559, medium, tags: array, string, prefix-sum.
LeetCode 408 LintCode 637 Valid Word Abbreviation
Published:Dec 9, 2024 at 06:23 AM
Solutions for LeetCode 408 LintCode 637, easy, tags: two pointers, string, companies: facebook, google.
LeetCode 423 LintCode 1247 Reconstruct Original Digits from English
Published:Dec 19, 2024 at 06:23 AM
Solutions for LeetCode 423 LintCode 1247, medium, tags: hash table, simulation, math, string.
Analyze Recursive Algorithm Time Complexity for LeetCode Questions with Substitution, Recursion Tree and Master Theorem
Published:Dec 15, 2024 at 06:23 AM
Analyze Recursive Algorithm Time Complexity for LeetCode Questions with Substitution, Recursion Tree and Master Theorem
Rust Option, Rc, and RefCell Explained - LeetCode Tree Node and LinkedList Node
Published:Dec 11, 2024 at 07:23 AM
Explanation for rust data structure for tree node and linked list node. What is Rc and RefCell? Why Option<Rc<RefCell>>> three wrappers? How to avoid circular reference?
LintCode 26 Inner Product
Published:Dec 6, 2024 at 06:23 AM
Solutions for LintCode 26, hard, tags: dynamic programming.
LintCode 2503 Thread Safe Counter (Concurrency)
Published:Dec 18, 2024 at 06:23 AM
Solutions for LintCode 2503, tags: lock, re-entrant lock.

November ⁴⁴

Add Discord and Disqus to your web site
Updated:Nov 10, 2024 at 10:12 AM
add discord and disqus to this site
Fun Bit Tricks (Manipulations)
Published:Nov 26, 2024 at 10:23 AM
Fun bitwise tricks such as count set bits, negate, ilog2, xor swap, .etc.
LeetCode 314 LintCode 651 Binary Tree Vertical Order Traversal
Updated:Nov 10, 2024 at 10:12 AM
solutions for LeetCode 314 LintCode 651 Binary Tree Vertical Order Traversal, tags: hash, bfs, tree, companies: facebook google
Database (MongoDB, Microsoft SQL Server) CheatSheet
Updated:Nov 1, 2024 at 10:12 AM
tips for using mongodb
Cheatsheet for Math Knowledge Needed for LeetCode Algorithm Questions (Geometric Series and Arithmetic Progression Sum)
Published:Nov 28, 2024 at 06:23 AM
cheatsheet for math knowledge needed for leetcode algorithm questions, geometric series sum
Vim CheatSheet
Updated:Nov 22, 2024 at 10:12 AM
tips for using vim
CheatSheet for Windows Development
Updated:Nov 1, 2024 at 10:12 AM
tips for software development in Windows Operating System
Elevator Closest Floors (Shortest Path, Related to Shortest Seek Time First Disk Seek Algorithm)
Updated:Nov 21, 2024 at 07:23 AM
Solutions for Elevator Shortest Path, medium, tags: array, binary search.
How to Mark All as Read for Google Voice
Updated:Nov 18, 2024 at 10:12 AM
tips for using google voice, mark all as read
HackerRank Bitwise Xor Operations
Published:Nov 27, 2024 at 08:23 AM
Solutions for hackerrank bitwise xor operations, medium, tags: bit, companies: salesforce.
LeetCode 1 Similar Two Subtract Count
Published:Nov 24, 2024 at 07:23 AM
Solutions for LeetCode 1 similar, medium, tags: array, hash table, companies: salesforce.
LeetCode 38 LintCode 420 Count and Say (Look and Say)
Updated:Nov 23, 2024 at 07:23 AM
Solutions for LeetCode 38, LintCode 420, medium, tags: math, string, simulation, companies: facebook, pinterest.
Reverse of LeetCode 38 LintCode 420 Count and Say (Look and Say)
Updated:Nov 23, 2024 at 08:23 AM
Solutions for LeetCode 38, LintCode 420, medium, tags: math, string, simulation, companies: facebook, pinterest.
LeetCode 91 Decode Ways and Hacker Rank ASCII Encoded Strings (VMWare, Goldman Sachs, and Salesforce Interview Questions)
Published:Nov 28, 2024 at 07:23 AM
Solutions for LeetCode 91, medium, tags: string, dynamic programming, companies: goldman sachs, vmware, salesforce.
LeetCode 146 LintCode 134 LRU Cache
Published:Nov 24, 2024 at 09:23 AM
Solutions for LeetCode 146 LintCode 134, medium, tags: hash, linked list, design, doubly linked list, companies: amazon, openai.
LeetCode 487 LintCode 883 Max Consecutive Ones II
Published:Nov 24, 2024 at 08:23 AM
Solutions for LeetCode 487, LintCode 833, medium, tags: array, dynamic programming, sliding window, two pointers, companies: google.
LeetCode 811 LintCode 1006 Subdomain Visit Count
Published:Nov 24, 2024 at 06:23 AM
Solutions for LeetCode 811 and LintCode 1006, medium, tags: array, hash, string, counting, companies: salesforce.
LeetCode 1041 LintCode 1345 Robot Bounded in Circle (GeeksForGeeks, HackerRank EnCircular)
Published:Nov 30, 2024 at 07:23 AM
Solutions for LeetCode 1041 LintCode 1345 GFG HackerRank, medium, tags: math, string, simulation, companies: linkedin, salesforce.
LeetCode 1055 LintCode 3652 Shortest Way to Form String
Published:Nov 17, 2024 at 05:23 AM
Solutions for LeetCode 1055 LintCode 3652, hard, tags: greedy, two pointers, string.
LeetCode 1192 LintCode 1271 Critical Connections in a Network
Updated:Nov 10, 2024 at 10:12 AM
solutions for LeetCode 1192, LintCode 1271, hard, tags: dfs, graph, bi-connected component. Companies: Amazon.
LeetCode 125 LintCode 415 Valid Palindrome
Updated:Nov 13, 2024 at 08:12 AM
Solutions for LeetCode 125, LintCode 415, easy, tags: two pointers, string. Companies: LinkedIn, Facebook, Uber, Zenefits, Microsoft.
LeetCode 1346 Check If N and Its Double Exist
Published:Nov 29, 2024 at 06:23 AM
Solutions for LeetCode 1346, easy, tags: array, hash table, two pointers, binary search, sorting.
LeetCode 1574 Shortest Subarray to be Removed to Make Array Sorted
Updated:Nov 10, 2024 at 07:22 AM
Solutions for LeetCode 1574, medium, tags: array, binary-search, two-pointers.
LeetCode 1652 Defuse the Bomb
Updated:Nov 17, 2024 at 07:22 AM
Solutions for LeetCode 1652, easy, tags: array, sliding window.
LeetCode 1804 LintCode 3729 Implement Trie II
Updated:Nov 23, 2024 at 09:23 AM
Solutions for LeetCode 1804 LintCode 3729, medium, tags: design, trie, hash, string.
LeetCode 1930 Unique Length-3 Palindromic Subsequences
Updated:Nov 12, 2024 at 09:12 AM
Solutions for LeetCode 1930, medium, tags: hash, string, bit, prefix sum.
LeetCode 2064 Minimized Maximum of Products Distributed to Any Store
Updated:Nov 12, 2024 at 05:12 AM
Solutions for LeetCode 2064, medium, tags: array, binary search, heap.
LeetCode 214 LintCode 678 Shortest Palindrome (GeeksForGeeks Minimum Insertion to Form Shortest Palindrome)
Published:Nov 26, 2024 at 06:23 AM
Solutions for LeetCode 239, LintCode 678, medium, tags: two pointers, string, kmp, rabin-karp, rolling hash.
LeetCode 2257 Count Unguarded Cells in the Grid
Updated:Nov 20, 2024 at 07:23 AM
Solutions for LeetCode 2257, medium, tags: array, graph, simulation.
LeetCode 2461 Maximum Sum of Distinct Subarrays With Length K
Published:Nov 17, 2024 at 07:23 AM
Solutions for LeetCode 2461, medium, tags: array, sliding window, hash.
LeetCode 2563 Count the Number of Fair Pairs
Updated:Nov 11, 2024 at 09:12 AM
Solutions for LeetCode 2563, medium, tags: array, two pointers, binary search, sorting.
LeetCode 3043 Find the Length of the Longest Common Prefix
Updated:Nov 11, 2024 at 10:12 AM
solutions for LeetCode 3043, hard, tags: trie, string, array, hash.
LeetCode 3167 HackerRank Better Compression
Published:Nov 26, 2024 at 07:23 AM
Solutions for LeetCode 3167 HackerRank Better Compression, tags: string, hash table, companies: salesforce.
LeetCode 3254 Find the Power of K-Size Subarrays I
Updated:Nov 14, 2024 at 07:22 AM
Solutions for LeetCode 3254, medium, tags: array, sliding window.
LeetCode 465 LintCode 707 Optimal Account Balancing
Updated:Nov 22, 2024 at 07:24 AM
Solutions for LeetCode 465 LintCode 707, hard, tags: bit, array, dynamic programming, backtracking, bitmask.
LeetCode 862 LintCode 1507 Shortest Subarray with Sum at Least K
Updated:Nov 15, 2024 at 07:22 AM
Solutions for LeetCode 862, LintCode 1507, hard, tags: array, queue, sliding window, heap, monotonic queue, binary search, prefix sum.
LeetCode 239 LintCode 362 Sliding Window Maximum
Updated:Nov 10, 2024 at 10:12 AM
solutions for LeetCode 239, LintCode 362, hard, tags: array, queue, sliding window, heap, monotonic queue. Companies: Amazon, Zenefits, Microsoft, Google.
LintCode 2894 Order by frequency
Updated:Nov 16, 2024 at 07:22 AM
Solutions for LintCode 2894, medium, tags: map, sort. Related to LeetCode 884 and 451.
LintCode 3127 How Many Times is Two Squared?
Published:Nov 30, 2024 at 06:23 AM
Solutions for LintCode 3127, easy, tags: math, bit.
LeetCode 3133 Minimum Array End (bit)
Updated:Nov 9, 2024 at 05:12 PM
Solution for leetcode 3133 Minimum Array End, tags: bit
LeetCode 3097 Shortest Subarray With OR at Least K II (bit)
Updated:Nov 9, 2024 at 05:12 PM
solution for leetcode 3097 Shortest Subarray With OR at Least K II, tags: bit, sliding-window, array
LintCode 179 Update Bits (bit)
Updated:Nov 10, 2024 at 05:12 PM
solution for lintcode 179 update bits, tags: bit
LeetCode 20 LintCode 423 Valid Parentheses (stack)
Updated:Nov 8, 2024 at 05:12 PM
solution for LeetCode 20 LintCode 423 valid parentheses, tags: stack, string; companies: goldman sachs, twitter, airbnb, amazon, facebook, microsoft, bloomberg, uber, google.
How to Embed an SVG Image/Picture with the Code or File on a Website
Published:Nov 23, 2024 at 03:23 AM
three main ways to embed an SVG image or picture as a file or using html code on a website

October ²

Mac Tips and Great Apps
Updated:Oct 1, 2024 at 10:12 AM
tips for using mac
Cheatsheet for Python Data/AI Projects (Conda, Docker, Jupyter Notebook)
Updated:Oct 10, 2024 at 10:12 AM
tips and cheatsheet for python data/AI projects using conda, docker, and jupyter notebook

Archives

System Design - How do Websockets Work

LeetCode 658 LintCode 460 Find K Closest Elements

LeetCode 2539 LintCode 3855 Count the Number of Good Subsequences

LeetCode 2450 LintCode 3841 Number of Distinct Binary Strings After Applying Operations

System Design - Event Loop for Concurrent Applications

HackerRank and GeeksForGeeks Minimum Replacements/Substitutions to Make Adjacent Characters Unequal

How could we interview job candidates to find the right teammates? Why should we care?

LeetCode 206 LintCode 35 Reverse Linked List

LeetCode 532 LintCode 1187 K-diff Pairs in An Array

LeetCode 916 LintCode 1726 Word Subsets

LeetCode 1166 LintCode 3677 Design File System

LeetCode 1400 Construct K Palindrome Strings

LeetCode 1930 Unique Length-3 Palindromic Subsequences

LeetCode 2017 Grid Game

LeetCode 542 LintCode 974 01 Matrix and LeetCode 1765 Map of Highest Peak

LeetCode Meeting Rooms Derivative Question

Generative AI (Artificial Intelligence) with Large Language Models (LLM) - Part 1

AWS (Amazon Web Services) Tips and Cheatsheet

How to Draw Circles and Arcs with Python Library Matplotlib

How to Install SortedContainers in the Python Shell or With a Python Script

Java CheatSheet

Linux Cheatsheet, tips and Commands

HackerRank GET Requests for GIF Images

HackerRank Programmer Strings

HackerRank Robot Walks and Project Euler 208 Solutions

LeetCode 1 LintCode 56 Two Sum

LeetCode 53 LintCode 41 Maximum Subarray

LeetCode 339 LintCode 551 Nested List Weight Sum

LeetCode 520 LintCode 1202 IPO

LeetCode 540 LintCode 1183 Single Element in a Sorted Array

LeetCode 691 LintCode 1081 Stickers to Spell Word

LeetCode 713 LintCode 1075 Subarray Product Less Than K

LeetCode 875 LintCode 1492 Koko Eating Bananas

LeetCode 994 LintCode 3726 Rotting Oranges

LeetCode 1422 Maximum Score After Splitting a String

LeetCode 1650 LintCode 474 Lowest Common Ancestor of a Binary Tree III

LeetCode 2415 Reverse Odd Levels of Binary Tree

LeetCode 2466 LintCode 3854 Count Ways to Build Good Strings (Number of Good Binary Strings)

LeetCode 2558 Take Gifts From the Richest Pile

LeetCode 2559 Count Vowel Strings in Ranges

LeetCode 408 LintCode 637 Valid Word Abbreviation

LeetCode 423 LintCode 1247 Reconstruct Original Digits from English

Analyze Recursive Algorithm Time Complexity for LeetCode Questions with Substitution, Recursion Tree and Master Theorem

Rust Option, Rc, and RefCell Explained - LeetCode Tree Node and LinkedList Node

LintCode 26 Inner Product

LintCode 2503 Thread Safe Counter (Concurrency)

Add Discord and Disqus to your web site

Fun Bit Tricks (Manipulations)

LeetCode 314 LintCode 651 Binary Tree Vertical Order Traversal

Database (MongoDB, Microsoft SQL Server) CheatSheet

Cheatsheet for Math Knowledge Needed for LeetCode Algorithm Questions (Geometric Series and Arithmetic Progression Sum)

Vim CheatSheet

CheatSheet for Windows Development

Elevator Closest Floors (Shortest Path, Related to Shortest Seek Time First Disk Seek Algorithm)

How to Mark All as Read for Google Voice

HackerRank Bitwise Xor Operations

LeetCode 1 Similar Two Subtract Count

LeetCode 38 LintCode 420 Count and Say (Look and Say)

Reverse of LeetCode 38 LintCode 420 Count and Say (Look and Say)

LeetCode 91 Decode Ways and Hacker Rank ASCII Encoded Strings (VMWare, Goldman Sachs, and Salesforce Interview Questions)

LeetCode 146 LintCode 134 LRU Cache

LeetCode 487 LintCode 883 Max Consecutive Ones II

LeetCode 811 LintCode 1006 Subdomain Visit Count

LeetCode 1041 LintCode 1345 Robot Bounded in Circle (GeeksForGeeks, HackerRank EnCircular)

LeetCode 1055 LintCode 3652 Shortest Way to Form String

LeetCode 1192 LintCode 1271 Critical Connections in a Network

LeetCode 125 LintCode 415 Valid Palindrome

LeetCode 1346 Check If N and Its Double Exist

LeetCode 1574 Shortest Subarray to be Removed to Make Array Sorted

LeetCode 1652 Defuse the Bomb

LeetCode 1804 LintCode 3729 Implement Trie II

LeetCode 1930 Unique Length-3 Palindromic Subsequences

LeetCode 2064 Minimized Maximum of Products Distributed to Any Store

LeetCode 214 LintCode 678 Shortest Palindrome (GeeksForGeeks Minimum Insertion to Form Shortest Palindrome)

LeetCode 2257 Count Unguarded Cells in the Grid

LeetCode 2461 Maximum Sum of Distinct Subarrays With Length K

LeetCode 2563 Count the Number of Fair Pairs

LeetCode 3043 Find the Length of the Longest Common Prefix

LeetCode 3167 HackerRank Better Compression