Want to explore a graph deeply instead of level by level?
That’s exactly what Depth First Search (DFS) is built for

In today’s video, I explained DFS concept and then implemented it completely from scratch in Java — no built-in graph or list libraries used. Every structure, class, and traversal step is written manually and explained with dry run and logic flow.

This is the kind of DFS implementation that builds real interview-level understanding, not just syntax memory.

WHAT YOU WILL LEARN IN THIS VIDEO:

* What is Depth First Search (DFS)
* When DFS should be used
* Why DFS is used for deep exploration problems
* Creating Node class from scratch
* Creating Graph class manually
* Maintaining Adjacency List without built-ins
* Adding edges for undirected graph (both directions)
* Marking visited nodes to prevent revisits
* Why visited tracking is critical
* DFS traversal using recursion
* How recursion drives depth exploration
* Full program dry run step by step
* Running program and verifying output
* Quick DFS vs BFS difference
* Time Complexity explained clearly → O(V + E)

INTERVIEW INTELLIGENCE
Interviewers often ask:
* Why DFS uses recursion or stack
* How to prevent infinite cycles
* Difference between DFS and BFS use cases
* When DFS is better than BFS

This video prepares you to answer all of these with logic — not memorized lines.

BEST USE CASES OF DFS
* Path existence checking
* Cycle detection
* Topological style traversal
* Backtracking problems
* Maze and puzzle exploration

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Source Code:
https://github.com/farzeen-ali/DSA-Concepts-The-Techzeen-2025

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https://github.com/farzeen-ali/DSA-Lectures-2025-The-Techzeen

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