Number of Islands (LeetCode 200) | Full solution with a DFS and a BFS approach

Nikhil Lohia February 18, 2025
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Nikhil Lohia

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I want to share with you my knowledge, that I have gained all my life. I like to see every task in your day to day life as an interesting problem to solve, and if you can understand the requirements, solving for it can become somewhat intuitive. I try to explore certain aspects of day to day life and how I can make them easier for you. This involves daily hacks, tutorials, innovations, new discoveries, experiences and all the stuff I find amusing. As a software engineer myself, I also believe that good problem solving skills can help you overcome most of the barriers in life. Programming is one of them. If you know how to approach a problem, writing a code for it in any language could be a very typical task. With this channel I aim to focus on the way to solve a problem efficiently rather than just its implementation.

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Join this channel to get access to perks: https://www.youtube.com/channel/UCT-S2ngqEBoYCM5UKuNeELg/join Actual problem on LeetCode: https://leetcode.com/problems/number-of-islands/description/ Chapters: 00:00 - Intro 00:42 - Problem Statement 01:30 - A visual treat 03:49 - A logical approach 05:54 - A programmable approach 09:45 - Thought to pseudo code 13:31 - Dry run of Code 17:38 - Bonus, A BFS approach 18:59 - Final Thoughts 📚 Links to topics I talk about in the video: Depth first Search: https://youtu.be/bOrCi635kUw Breadth First Search: https://youtu.be/zfwHQNqszP4 Queues: https://youtu.be/j-lKqN_NNUE Other Medium Problems: https://www.youtube.com/playlist?list=PLFdAYMIVJQHO1paovM-tu2vtGzQU72z_U 📘 A text based explanation is available at: https://studyalgorithms.com Code on Github: https://github.com/nikoo28/java-solutions/blob/master/src/main/java/leetcode/medium/NumberOfIslands.java Test-cases on Github: https://github.com/nikoo28/java-solutions/blob/master/src/test/java/leetcode/medium/NumberOfIslandsTest.java 📖 Reference Books: Starting Learn to Code: https://amzn.to/3sJm8Wl Favorite book to understand algorithms: https://amzn.to/4848xJH Favorite book for data structures: https://amzn.to/3P96YBv Get started for interview preparation: https://amzn.to/44Nn5du 🔗 To see more videos like this, you can show your support on: https://www.buymeacoffee.com/studyalgorithms 🎥 My Recording Gear: Recording Light: https://amzn.to/3PdsViT Microphone: https://amzn.to/3Exv83x Recording Camera: https://amzn.to/3PwyN8e Tablet to sketch and draw: https://amzn.to/3ZdKVy7 Sketching Tool: https://amzn.to/45XJEgY Laptop to edit videos: https://amzn.to/460ofDu 💻 Get Social 💻 Follow on Facebook at: https://www.facebook.com/studyalgos Subscribe to RSS feeds: https://studyalgorithms.com/feed/ Join fan mail: http://eepurl.com/g9Dadv #leetcode #programming #interview

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