Flood Fill & Grid Graphs
Implicit graphs, 4/8-connectivity, island counting, and boundary fill problems.
32 lessons
96 min
Lessons
1. Intro
Theory vs Practice
2m
2. The Paint Bucket
Visualizing Flood Fill
2m
3. Counting Islands
From Pixels to Geography
2m
4. Dependencies and Cycles
The Impossible Schedule
2m
5. Cycle Detection - The Logic
DFS Recursion Stack
4m
6. The Three Colors
State Management
4m
7. Cycle Detection - Visualizing
Walking the path
3m
8. Quiz: Grid Graph Traversal
Knowledge check
2m1 problems
9. Not Every Grid Needs Traversal
Counting vs exploring
3m
10. Quiz: Cycle Detection in Directed Graphs
Knowledge check
2m1 problems
11. LeetCode 733 Flood Fill - Problem Statement
LeetCode 733
2m1 problems
12. LeetCode 733 Flood Fill - Strategy
DFS or BFS?
3m
13. LeetCode 733 Flood Fill - Why It Works
The Chain Reaction
3m
14. LeetCode 733 Flood Fill - Implementation
Coding the Solution
5m1 problems
15. LeetCode 200 Number of Islands - Problem Statement
LeetCode 200
2m1 problems
16. LeetCode 200 Number of Islands - Core Idea
Find and Erase
3m
17. LeetCode 200 Number of Islands - Visualization
Sinking the Island
3m
18. LeetCode 200 Number of Islands - Implementation
Coding the Sinking Strategy
6m1 problems
19. Quiz: Island Counting Logic
Knowledge check
2m1 problems
20. LeetCode 463 Island Perimeter - Problem Statement
LeetCode 463
2m1 problems
21. LeetCode 463 Island Perimeter - Core Idea
Count exposed edges
3m
22. LeetCode 463 Island Perimeter - Algorithm
Count, do not traverse
4m
23. LeetCode 463 Island Perimeter - Implementation
Edge counting code
5m1 problems
24. LeetCode 463 Island Perimeter - Lessons
Not all grid problems need DFS
3m
25. Quiz: Perimeter vs Area
Knowledge check
2m1 problems
26. LeetCode 695 Max Area of Island - Problem Statement
DFS with size tracking
6m1 problems
27. LeetCode 695 Max Area of Island - Core Idea
DFS returns size
3m
28. LeetCode 695 Max Area of Island - Algorithm
Recursive area calculation
4m
29. LeetCode 695 Max Area of Island - Implementation
LeetCode 695
2m1 problems
30. LeetCode 695 Max Area of Island - Lessons
DFS as a calculator
3m
31. Quiz: Flood Fill Boundaries
Knowledge check
2m1 problems
32. Section Recap
What we learned
2m
Practice Problems
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