CodingNinja

@UC9RMNwYTL3SXCP6ShLWVFww - 27.4K subscribers

Hi Everyone! My name is Ken. I used to work for Amazon. Let's solve the interview questions by using LeetCode. I'll explain how to solve the question and write codes with drawing charts or pictures. I believe that this channel helps you prepare for your coming technical interviews as a software engineer! Feel free to ask me if you have any questions or you don't understand what I say in the videos. Your comments and requests are always more than welcome! As of Dec 31 2022, I work as a software engineer for a startup company and focus on mobile application and backend.

Home Videos Live Playlists

Longest Palindrome LeetCode 409 | Even and Odd Counts Matter

Longest Palindrome LeetCode 409 | Even and Odd Counts Matter CodingNinja

125 views - 1 week ago

The Best Way to Support Your Engineering Career and Growth | Membership Tiers Explained

The Best Way to Support Your Engineering Career and Growth | Membership Tiers Explained CodingNinja

2.6K views - 3 weeks ago

The Right Order: My Personal System Design Interview Framework

The Right Order: My Personal System Design Interview Framework CodingNinja

3 weeks ago

LeetCode 412 Fizz Buzz Explained | Learn Conditional Logic the Right Way

LeetCode 412 Fizz Buzz Explained | Learn Conditional Logic the Right Way CodingNinja

230 views - 1 month ago

Big O Notation - What Every Developer Must Know

Big O Notation - What Every Developer Must Know CodingNinja

1 month ago

Find All Disappeared Numbers - LeetCode 448 | Master This Array Problem Fast!

Find All Disappeared Numbers - LeetCode 448 | Master This Array Problem Fast! CodingNinja

389 views - 1 month ago

Network Fundamentals for Software Engineers

Network Fundamentals for Software Engineers CodingNinja

1 month ago

Database Fundamentals for Beginners: Tables, SQL, Indexing & Transactions

Database Fundamentals for Beginners: Tables, SQL, Indexing & Transactions CodingNinja

1 month ago

Server vs. PC: It’s Not the Hardware, It’s the Role.

Server vs. PC: It’s Not the Hardware, It’s the Role. CodingNinja

1 month ago

Longest Valid Parentheses - LeetCode 32 | Solve the Parentheses Puzzle Fast!

Longest Valid Parentheses - LeetCode 32 | Solve the Parentheses Puzzle Fast! CodingNinja

2 months ago

Word Pattern - Leetcode 290 | No Need for Two HashMaps!

Word Pattern - Leetcode 290 | No Need for Two HashMaps! CodingNinja

498 views - 3 months ago

Repeated DNA Sequences - LeetCode 187 | Efficient Solution for Interviews

Repeated DNA Sequences - LeetCode 187 | Efficient Solution for Interviews CodingNinja

4 months ago

【Two Pointers】These Are The Exact Questions I Got In a Tech Interview

【Two Pointers】These Are The Exact Questions I Got In a Tech Interview CodingNinja

4 months ago

【Graph with BFS and DFS】These Are The Exact Questions I Got In a Tech Interview

【Graph with BFS and DFS】These Are The Exact Questions I Got In a Tech Interview CodingNinja

4 months ago

【HashMap】These Are The Exact Questions I Got In a Tech Interview

【HashMap】These Are The Exact Questions I Got In a Tech Interview CodingNinja

4 months ago

【String】These Are The Exact Questions I Got In a Tech Interview

【String】These Are The Exact Questions I Got In a Tech Interview CodingNinja

4 months ago

Two Sum IV - Input is a BST - leetcode 653 | Preorder, Inorder and Postorder Solution

Two Sum IV - Input is a BST - leetcode 653 | Preorder, Inorder and Postorder Solution CodingNinja

435 views - 5 months ago

【Data Structure - Hash Tables Vol.2】Hash Function

【Data Structure - Hash Tables Vol.2】Hash Function CodingNinja

5 months ago

【Data Structure - Hash Tables Vol.1】Hash Tables Introduction

【Data Structure - Hash Tables Vol.1】Hash Tables Introduction CodingNinja

5 months ago

Increasing Triplet Subsequence - LeetCode 334 Explained Simply

Increasing Triplet Subsequence - LeetCode 334 Explained Simply CodingNinja

5 months ago

Binary Tree Postorder Traversal Made Super Easy! - leetcode 145

Binary Tree Postorder Traversal Made Super Easy! - leetcode 145 CodingNinja

365 views - 5 months ago

【Data Structure - Array Vol.2】Static vs Dynamic Arrays

【Data Structure - Array Vol.2】Static vs Dynamic Arrays CodingNinja

5 months ago

Remove Duplicates from Sorted List II - LeetCode #82

Remove Duplicates from Sorted List II - LeetCode #82 CodingNinja

5 months ago

【Data Structure Array - Vol.1】Arrays introduction

【Data Structure Array - Vol.1】Arrays introduction CodingNinja

5 months ago

Next Greater Element II - LeetCode 503 | Stop Overthinking, Try This

Next Greater Element II - LeetCode 503 | Stop Overthinking, Try This CodingNinja

6 months ago

Next Greater Element I - LeetCode 496 | Stop Overthinking, Try This

Next Greater Element I - LeetCode 496 | Stop Overthinking, Try This CodingNinja

1.2K views - 6 months ago

Join a Membership for Just 90 Yen!? (Only USD $0.61! as of Aug 14th, 2025)

Join a Membership for Just 90 Yen!? (Only USD $0.61! as of Aug 14th, 2025) CodingNinja

10.1K views - 6 months ago

Single Element in a Sorted Array - LeetCode 540 | Stop Overthinking, Try This

Single Element in a Sorted Array - LeetCode 540 | Stop Overthinking, Try This CodingNinja

6 months ago

Sqrt(x) - LeetCode 69: thought process with slide presentation

Sqrt(x) - LeetCode 69: thought process with slide presentation CodingNinja

6 months ago

【No ad】Sqrt(x) - LeetCode 69: Master the Square Root Problem in Minutes!

【No ad】Sqrt(x) - LeetCode 69: Master the Square Root Problem in Minutes! CodingNinja

6 months ago

Sqrt(x) - LeetCode 69: Master the Square Root Problem in Minutes!

Sqrt(x) - LeetCode 69: Master the Square Root Problem in Minutes! CodingNinja

2.1K views - 6 months ago

Best Time to Buy and Sell Stock III - LeetCode 123: How to Approach It Like a Pro

Best Time to Buy and Sell Stock III - LeetCode 123: How to Approach It Like a Pro CodingNinja

6 months ago

Edit Distance - LeetCode 72: Insert, Delete, or Replace?

Edit Distance - LeetCode 72: Insert, Delete, or Replace? CodingNinja

6 months ago

Word Ladder - LeetCode 127: This One Trick Makes It Lightning Fast ⚡

Word Ladder - LeetCode 127: This One Trick Makes It Lightning Fast ⚡ CodingNinja

6 months ago

Single Number LeetCode 136 | No HashMap Needed! Bitwise Magic

Single Number LeetCode 136 | No HashMap Needed! Bitwise Magic CodingNinja

3.3K views - 7 months ago

String to Integer (atoi) LeetCode 8 | Easy & Clear Explanation for Beginners

String to Integer (atoi) LeetCode 8 | Easy & Clear Explanation for Beginners CodingNinja

2.7K views - 7 months ago

Reverse Nodes in k-Group LeetCode 25 | Easy & Clear Explanation for Beginners

Reverse Nodes in k-Group LeetCode 25 | Easy & Clear Explanation for Beginners CodingNinja

7 months ago

Convert Sorted Array to Binary Search Tree LeetCode 108 | Easy & Clear Explanation for Beginners

Convert Sorted Array to Binary Search Tree LeetCode 108 | Easy & Clear Explanation for Beginners CodingNinja

1.7K views - 7 months ago

Rotate List LeetCode 61 | Easy & Clear Explanation for Beginners

Rotate List LeetCode 61 | Easy & Clear Explanation for Beginners CodingNinja

7 months ago

Max Consecutive Ones LeetCode 485 | Easy & Clear Explanation for Beginners

Max Consecutive Ones LeetCode 485 | Easy & Clear Explanation for Beginners CodingNinja

782 views - 8 months ago

Max Consecutive Ones III LeetCode 1004 - Don’t Miss This Trick with k!

Max Consecutive Ones III LeetCode 1004 - Don’t Miss This Trick with k! CodingNinja

8 months ago

Palindrome Linked List LeetCode 234 - Intuitive Guide + Code

Palindrome Linked List LeetCode 234 - Intuitive Guide + Code CodingNinja

843 views - 8 months ago

Two Sum LeetCode 1 - How I Solve It in Interviews

Two Sum LeetCode 1 - How I Solve It in Interviews CodingNinja

66.7K views - 9 months ago

Median of Two Sorted Arrays LeetCode 4 - Intuitive Guide + Code

Median of Two Sorted Arrays LeetCode 4 - Intuitive Guide + Code CodingNinja

11.7K views - 9 months ago

Find Numbers with Even Digits LeetCode 1295 Explained in Python

Find Numbers with Even Digits LeetCode 1295 Explained in Python CodingNinja

337 views - 9 months ago

Binary Tree Right Side View LeetCode 199

Binary Tree Right Side View LeetCode 199 CodingNinja

10 months ago

Balanced Binary Tree Leetcode 110 Explained – Efficient Approach & Code Walkthrough

Balanced Binary Tree Leetcode 110 Explained – Efficient Approach & Code Walkthrough CodingNinja

2.2K views - 10 months ago

Nested Loops Explained: O(n) vs O(n²) Time Complexity

Nested Loops Explained: O(n) vs O(n²) Time Complexity CodingNinja

10 months ago

Partition Equal Subset Sum LeetCode 416 - Can You Split Arrays Into Equal Sums?

Partition Equal Subset Sum LeetCode 416 - Can You Split Arrays Into Equal Sums? CodingNinja

11 months ago

The Most Common Coding Interview Question SOLVED!

The Most Common Coding Interview Question SOLVED! CodingNinja

11 months ago

Master Anagrams in Python With This Simple Trick!

Master Anagrams in Python With This Simple Trick! CodingNinja

1 year ago

Lowest Common Ancestor of a Binary Tree LeetCode 236

Lowest Common Ancestor of a Binary Tree LeetCode 236 CodingNinja

1 year ago

Master the Sliding Window Technique: 4 Must-Know Problems Explained

Master the Sliding Window Technique: 4 Must-Know Problems Explained CodingNinja

1 year ago

Lowest Common Ancestor of a Binary Search Tree LeetCode 235

Lowest Common Ancestor of a Binary Search Tree LeetCode 235 CodingNinja

1 year ago

Top 5 Must-Solve Linked List Problems on LeetCode (Merge, Reverse, Cycle Detection & More!)

Top 5 Must-Solve Linked List Problems on LeetCode (Merge, Reverse, Cycle Detection & More!) CodingNinja

1 year ago

Kth Largest Element in an Array LeetCode 215 | Intuitive Explanation + Code

Kth Largest Element in an Array LeetCode 215 | Intuitive Explanation + Code CodingNinja

1 year ago

Master Dynamic Programming | 5 Key Problems for Coding Interviews

Master Dynamic Programming | 5 Key Problems for Coding Interviews CodingNinja

1 year ago

Subarray Sum Equals K LeetCode 560 | Intuitive Explanation + Code

Subarray Sum Equals K LeetCode 560 | Intuitive Explanation + Code CodingNinja

1 year ago

Valid Palindrome LeetCode 125 | Intuitive Explanation + Code

Valid Palindrome LeetCode 125 | Intuitive Explanation + Code CodingNinja

6K views - 1 year ago

Greatest Common Divisor of Strings LeetCode 1071 - Intuitive Guide + Code

Greatest Common Divisor of Strings LeetCode 1071 - Intuitive Guide + Code CodingNinja

5.8K views - 1 year ago