Detect Cycles in 2D Grid | LeetCode 1559 | DFS | Graph

In this video, we solve **LeetCode 1559: Detect Cycles in 2D Grid**, a classic problem that looks like a grid traversal — but is actually a **graph cycle detection problem**. 💡 The key insight: 👉 **GRID = GRAPH** Once you convert the grid into a graph, the solution becomes straightforward using **DFS with parent tracking**. --- 🚀 **What’s covered in this video:** ✅ Problem statement with clear visual example ✅ Grid → Graph transformation (most important insight) ✅ What is a cycle in a graph? ✅ Why parent tracking is necessary ✅ DFS approach step-by-step ✅ Full dry run (easy to follow) ✅ Clean and interview-ready code walkthrough --- 🧠 **Key Idea:** Each cell is a node, and edges exist between adjacent cells with the same value. We perform DFS and detect a cycle if we visit a node that is: ✔ Already visited ❌ Not the parent --- 🎯 **Why this problem is important:** * Frequently asked in interviews (Google, Amazon, Meta) * Builds strong intuition for **graph problems in grids** * Teaches a core DFS pattern: **cycle detection with parent** --- 🔥 **What you’ll learn:** * Converting grid problems into graph problems * DFS traversal with parent tracking * Cycle detection patterns * Writing clean and optimal code --- If you found this helpful: 👍 Like | 💬 Comment | 🔔 Subscribe --- #Leetcode #Graph #DFS #CodingInterview #problemsolving #Leetcode, #Leetcode1559, #GraphProblems, #DFS, #CycleDetection, #CodingInterview, #FAANG, #GoogleInterview, #AmazonInterview, #MetaInterview, #Algorithms, #DataStructures, #ProblemSolving, #CompetitiveProgramming, #CodingPractice, #JavaProgramming, #PythonCoding, #TechYouTube, #InterviewPreparation, #GridProblems