DSA Python 2025 – Detect Cycle in Undirected Graph | DFS with Parent Check | GFG – Part 125 [Hindi]

🚀 Welcome to Part 125 of Code & Debug’s DSA Python Course 2025!

In this video, we solve the Detect Cycle in an Undirected Graph problem from GeeksforGeeks using a Depth First Search (DFS) approach. We maintain a parent reference to correctly identify cycles without revisiting the edge we came from.

📚 What you’ll learn in this video:
✅ How cycle detection works in undirected graphs
✅ Why we need to track the parent of each node in DFS
✅ Recursive DFS implementation with visited array
✅ Building adjacency list from edge list
✅ Dry run + time and space complexity analysis

💡 Why is this important?
This DFS-based approach is a fundamental graph technique used in cycle detection, graph coloring, tree validation, and connected component analysis. It’s a frequent topic in coding interviews and online assessments.

👉 Practice the problem on GeeksforGeeks:
🔗 https://www.geeksforgeeks.org/problems/detect-cycle-in-an-undirected-graph/1

👉 Refer to the article for better understanding:
📌 https://codeanddebug.in/blog/detect-cycle-in-an-undirected-graph-using-dfs/

👉 📄 Access the full YouTube DSA Playlist Sheet (All Questions in Order):
🔗 https://docs.google.com/spreadsheets/d/1AWE15Fy3wD2iqu2vjK_R7cCiuvSsjYQclcdZmHpF66o/edit?usp=sharing

👉 Enroll in this FREE DSA Python course here:
🔗 https://codeanddebug.in/course/master-dsa-with-leetcode

👉 Enroll for Self-Paced Advanced DSA course here:
🔗 https://codeanddebug.in/course/zero-to-hero-python-dsa

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