1. Implement BFS to solve the "Word Ladder" problem.

2. Write a function to find the shortest path in a weighted graph with non-negative weights using BFS.

3. Implement a function to solve the "Knight's Tour" problem using BFS.

4. Write a function to find the shortest path in a grid with portals using BFS.

5. Implement a function to solve the "Jump Game" problem using BFS.

6. Write a function to find the shortest path in a grid with multiple sources and destinations using BFS.

7. Implement a function to find the shortest path in a binary matrix with obstacles using BFS.

8. Write a function to solve the "Minimum Jumps to Reach End" problem using BFS.

9. Implement a function to solve the "Rotting Oranges" problem using BFS.

10. Write a function to find the shortest path in a grid with keys and locks using BFS.

11. Implement a function to solve the "Open the Lock" problem using BFS.

12. Write a function to find the minimum number of steps to reach the end of a grid with traps using BFS.

13. Implement a function to find the shortest path in a directed graph using BFS.

14. Write a function to solve the "Bus Routes" problem using BFS.

15. Implement a function to find the shortest path in a grid with weights using BFS.

16. Write a function to solve the "Escape a Large Maze" problem using BFS.

17. Implement a function to find the shortest path in a graph with negative weights using BFS.

18. Write a function to solve the "Sliding Puzzle" problem using BFS.

19. Implement a function to find the shortest path in a grid with teleportation portals using BFS.

20. Write a function to solve the "Minimum Number of Steps to Convert One String to Another" problem using BFS.

21. Implement a function to find the shortest path in a grid with forbidden cells using BFS.

22. Write a function to solve the "Alien Dictionary" problem using BFS.

23. Implement a function to find the shortest path in a graph with multiple starting points using BFS.

24. Write a function to solve the "Shortest Path in Binary Matrix" problem using BFS.

25. Implement a function to find the shortest path in a grid with special move rules using BFS.

26. Write a function to solve the "Parallel Courses" problem using BFS.

27. Implement a function to find the shortest path in a maze with locked doors using BFS.

28. Write a function to solve the "Network Delay Time" problem using BFS.

29. Implement a function to find the shortest path in a grid with weighted obstacles using BFS.

30. Write a function to solve the "Race Car" problem using BFS.