1. Flooding
© 2018

2. Flooding If the spot on the drawing is not empty return
Color the spot using c
Create a to-do list with spot as its element
While the to-do list is not empty
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

3. Example

4. Suppose spot is ( 6, 12 )
spot on drawing is not empty, so no flooding to perform

5. Suppose spot is ( 7, 7 )
spot on drawing is empty, so there is flooding to perform

6. Flood drawing starting at spot ( 7, 7 ) using c

7. Flood drawing starting at spot ( 7, 7 ) using c

8. Flood drawing starting at spot ( 7, 7 ) using c

9. Paint spot
spot (7,7) c

10. Create to-do list
spot (7,7) c
to-do list

11. Add spot to to-do list
spot (7,7) c
to-do list
(7,7)

12. Loop while to-do list is not empty
spot (7,7) c
to-do list
(7,7)

13. Loop while to-do list is not empty
spot (7,7) c
to-do list
(7,7)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

14. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

15. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

16. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
(6,7)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

17. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
(6,7)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

18. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
(6,7)
(8,7)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

19. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
(6,7)
(8,7)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

20. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
(6,7)
(8,7)
(7,6)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

21. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
(6,7)
(8,7)
(7,6)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

22. Loop while to-do list is not empty
spot (7,7) c
v (7,7)
to-do list
(6,7)
(8,7)
(7,6)
(7,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

23. Loop while to-do list is not empty
spot (7,7) c
v (6,7)
to-do list
(8,7)
(7,6)
(7,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

24. Loop while to-do list is not empty
spot (7,7) c
v (6,7)
to-do list
(8,7)
(7,6)
(7,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

25. Loop while to-do list is not empty
spot (7,7) c
v (6,7)
to-do list
(8,7)
(7,6)
(7,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

26. Loop while to-do list is not empty
spot (7,7) c
v (6,7)
to-do list
(8,7)
(7,6)
(7,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

27. Loop while to-do list is not empty
spot (7,7) c
v (6,7)
to-do list
(8,7)
(7,6)
(7,8)
(6,6)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

28. Loop while to-do list is not empty
spot (7,7) c
v (6,7)
to-do list
(8,7)
(7,6)
(7,8)
(6,6)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

29. Loop while to-do list is not empty
spot (7,7) c
v (6,7)
to-do list
(8,7)
(7,6)
(7,8)
(6,6)
(6,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

30. Loop while to-do list is not empty
spot (7,7) c
v (8,7)
to-do list
(7,6)
(7,8)
(6,6)
(6,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

31. Loop while to-do list is not empty
spot (7,7) c
v (8,7)
to-do list
(7,6)
(7,8)
(6,6)
(6,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

32. Loop while to-do list is not empty
spot (7,7) c
v (8,7)
to-do list
(7,6)
(7,8)
(6,6)
(6,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

33. Loop while to-do list is not empty
spot (7,7) c
v (8,7)
to-do list
(7,6)
(7,8)
(6,6)
(6,8)
(9,7)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

34. Loop while to-do list is not empty
spot (7,7) c
v (8,7)
to-do list
(7,6)
(7,8)
(6,6)
(6,8)
(9,7)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

35. Loop while to-do list is not empty
spot (7,7) c
v (8,7)
to-do list
(7,6)
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

36. Loop while to-do list is not empty
spot (7,7) c
v (8,7)
to-do list
(7,6)
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

37. Loop while to-do list is not empty
spot (7,7) c
v (8,7)
to-do list
(7,6)
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
(8,8) y
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

38. Loop while to-do list is not empty
spot (7,7) c
v (7,6)
to-do list
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
(8,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

39. Loop while to-do list is not empty
spot (7,7) c
v (7,6)
to-do list
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
(8,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

40. Loop while to-do list is not empty
spot (7,7) c
v (7,6)
to-do list
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
(8,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

41. Loop while to-do list is not empty
spot (7,7) c
v (7,6)
to-do list
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
(8,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

42. Loop while to-do list is not empty
spot (7,7) c
v (7,6)
to-do list
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
(8,8)
(7,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

43. Loop while to-do list is not empty
spot (7,7) c
v (7,6)
to-do list
(7,8)
(6,6)
(6,8)
(9,7)
(8,6)
(8,8)
(7,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

44. Loop while to-do list is not empty
spot (7,7) c
v (7,8)
to-do list
(6,6)
(6,8)
(9,7)
(8,6)
(8,8)
(7,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

45. Loop while to-do list is not empty
spot (7,7) c
v (7,8)
to-do list
(6,6)
(6,8)
(9,7)
(8,6)
(8,8)
(7,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

46. Loop while to-do list is not empty
spot (7,7) c
v (6,6)
to-do list
(6,8)
(9,7)
(8,6)
(8,8)
(7,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

47. Loop while to-do list is not empty
spot (7,7) c
v (6,6)
to-do list
(6,8)
(9,7)
(8,6)
(8,8)
(7,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

48. Loop while to-do list is not empty
spot (7,7) c
v (6,6)
to-do list
(6,8)
(9,7)
(8,6)
(8,8)
(7,5)
(6,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

49. Loop while to-do list is not empty
spot (7,7) c
v (6,8)
to-do list
(9,7)
(8,6)
(8,8)
(7,5)
(6,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

50. Loop while to-do list is not empty
spot (7,7) c
v (6,8)
to-do list
(9,7)
(8,6)
(8,8)
(7,5)
(6,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

51. Loop while to-do list is not empty
spot (7,7) c
v (6,8)
to-do list
(9,7)
(8,6)
(8,8)
(7,5)
(6,5)
(5,8)
(6,9)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

52. Loop while to-do list is not empty
spot (7,7) c
v (9,7)
to-do list
(8,6)
(8,8)
(7,5)
(6,5)
(5,8)
(6,9)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

53. Loop while to-do list is not empty
spot (7,7) c
v (9,7)
to-do list
(8,6)
(8,8)
(7,5)
(6,5)
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

54. Loop while to-do list is not empty
spot (7,7) c
v (8,6)
to-do list
(8,8)
(7,5)
(6,5)
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

55. Loop while to-do list is not empty
spot (7,7) c
v (8,6)
to-do list
(8,8)
(7,5)
(6,5)
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

56. Loop while to-do list is not empty
spot (7,7) c
v (8,8)
to-do list
(7,5)
(6,5)
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

57. Loop while to-do list is not empty
spot (7,7) c
v (8,8)
to-do list
(7,5)
(6,5)
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

58. Loop while to-do list is not empty
spot (7,7) c
v (7,5)
to-do list
(6,5)
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

59. Loop while to-do list is not empty
spot (7,7) c
v (7,5)
to-do list
(6,5)
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
(7,4)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

60. Loop while to-do list is not empty
spot (7,7) c
v (6,5)
to-do list
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
(7,4)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

61. Loop while to-do list is not empty
spot (7,7) c
v (6,5)
to-do list
(5,8)
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
(7,4)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

62. Loop while to-do list is not empty
spot (7,7) c
v (5,8)
to-do list
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
(7,4)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

63. Loop while to-do list is not empty
spot (7,7) c
v (5,8)
to-do list
(6,9)
(10,7)
(9,6)
(9,8)
(8,5)
(7,4)
(4,8)
(5,9)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

64. Loop while to-do list is not empty
spot (7,7) c
v (6,9)
to-do list
(10,7)
(9,6)
(9,8)
(8,5)
(7,4)
(4,8)
(5,9)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

65. Loop while to-do list is not empty
spot (7,7) c
v (6,9)
to-do list
(10,7)
(9,6)
(9,8)
(8,5)
(7,4)
(4,8)
(5,9)
(6,10)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

66. Loop while to-do list is not empty
spot (7,7) c
v (10,7)
to-do list
(9,6)
(9,8)
(8,5)
(7,4)
(4,8)
(5,9)
(6,10)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list

67. Loop while to-do list is not empty
spot (7,7) c
v (10,7)
to-do list
(9,6)
(9,8)
(8,5)
(7,4)
(4,8)
(5,9)
(6,10)
(11,7)
(10,6)
(10,8)
Pop an element from the to-do list and assign it to v
If v’s left is empty, paint it and add to to-do list
If v’s right is empty, paint it and add to to-do list
If v’s above is empty, paint it and add to to-do list
If v’s below is empty, paint it and add to to-do list