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Stack and ArrayList

Stack and ArrayList. Array Based Collections. Collections. Arrays Primitive structured storage Collections Higher level storage structures Lists Stacks/Queues Sets Trees Graphs…. Stack. Collection where we can only work with "top" Peek() : get value on top

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Stack and ArrayList

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  1. Stack and ArrayList Array Based Collections

  2. Collections • Arrays • Primitive structured storage • Collections • Higher level storage structures • Lists • Stacks/Queues • Sets • Trees • Graphs…

  3. Stack • Collection where we can only work with "top" • Peek() : get value on top • Pop() : remove value on top • Push(value) : put new value on top

  4. Stack • LIFO : Last in First Out

  5. Internal Structure • Stack after pushing5, 10, 20 capacity = 10 size = 3elements = □

  6. Constructor • Default capacity = 10 • Array of uninitialized values capacity = 10 size = 0elements = □

  7. Push • Pushing 15 • Size indicates next available slot capacity = 10 size = 3elements = □

  8. Push • Pushing 15 • Size indicates next available slot capacity = 10 size = 3elements = □

  9. Push • Pushing 15 • Size indicates next available slot capacity = 10 size = 4elements = □

  10. Growing • When run out of roomallocate new array, copydelete old capacity = 5 size = 5elements = □

  11. Growing • When run out of roomallocate new array, copydelete old capacity = 5 size = 5elements = □ old = □

  12. Growing • When run out of roomallocate new array, copydelete old capacity = 10 size = 5elements = □ old = □

  13. Growing • When run out of roomallocate new array, copydelete old capacity = 10 size = 5elements = □ old = □

  14. Growing • When run out of roomallocate new array, copydelete old capacity = 10 size = 5elements = □ old = □

  15. Growing • When run out of roomallocate new array, copydelete old capacity = 10 size = 5elements = □

  16. Peek • Peek • Size – 1 indicates "top" element capacity = 10 size = 4elements = □ What can go wrong here?

  17. Pop • Pop • Predecrement happens before access • Old item not part of logical stack capacity = 10 size = 4elements = □

  18. Pop • Pop • Predecrement happens before access • Old item not part of logical stack capacity = 10 size = 3elements = □

  19. Usual Suspects • Manage memory so… • Copy Constructor • Destructor

  20. Split • Split • Return new Stackwith top half capacity = 10 size = 4elements = □

  21. Split • Split • Return new Stackwith top half top capacity = 10 size = 0elements = □ this capacity = 10 size = 4elements = □

  22. Split • Split • Return new Stackwith top half top capacity = 10 size = 0elements = □ this capacity = 10 size = 4elements = □ myNewSize = 2

  23. Split • Split • Return new Stackwith top half top capacity = 10 size = 1elements = □ this capacity = 10 size = 4elements = □ myNewSize = 2

  24. Split • Split • Return new Stackwith top half top capacity = 10 size = 2elements = □ this capacity = 10 size = 4elements = □ myNewSize = 2

  25. Split • Split • Return new Stackwith top half top capacity = 10 size = 2elements = □ this capacity = 10 size = 2elements = □ myNewSize = 2

  26. Split • Split • Return new Stackwith top half topPart capacity = 10 size =2elements = □ this capacity = 10 size = 2elements = □

  27. Clear • Clear • Change logical sizeto 0 capacity = 10 size = 4elements = □

  28. Clear • Clear • Change logical sizeto 0 capacity = 10 size = 0elements = □

  29. ArrayList • ArrayList • Acts like a list • Implemented with array

  30. Code Tour • Same structure as Stack • Pointer to dynamic array • Maintain logical/maximum size

  31. Code Tour • Constructor capacity = 10 currentSize = 0list = □

  32. Code Tour • Append 'U' capacity = 10 currentSize = 1list = □

  33. Code Tour • Insert 'Q' at 2 capacity = 10 currentSize = 4list = □

  34. Code Tour • Insert 'Q' at 2 capacity = 10 currentSize = 4list = □ i = 4

  35. Code Tour • Insert 'Q' at 2 capacity = 10 currentSize = 4list = □ i = 4

  36. Code Tour • Insert 'Q' at 2 capacity = 10 currentSize = 4list = □ i = 3

  37. Code Tour • Insert 'Q' at 2 capacity = 10 currentSize = 4list = □

  38. Code Tour • Insert 'Q' at 2 capacity = 10 currentSize = 5list = □

  39. Code Tour • Remove at 2 capacity = 10 currentSize = 5list = □

  40. Code Tour • Remove at 2 capacity = 10 currentSize = 5list = □ i = 2

  41. Code Tour • Remove at 2 capacity = 10 currentSize = 5list = □ i = 2

  42. Code Tour • Remove at 2 capacity = 10 currentSize = 5list = □ i = 3

  43. Code Tour • Remove at 2 capacity = 10 currentSize = 4list = □

  44. Search • Search for 'L' • Linear search capacity = 10 currentSize = 4list = □ How to rewrite this to have just one return statement?

  45. Sort • Selection Sort capacity = 10 currentSize = 4list = □ i = 0 currentMin = U currentMinIndex = 0

  46. Sort • Selection Sort capacity = 10 currentSize = 4list = □ i = 0 j = 1 currentMin = U currentMinIndex = 0

  47. Sort • Selection Sort capacity = 10 currentSize = 4list = □ i = 0 j = 1 currentMin = C currentMinIndex = 1

  48. Sort • Selection Sort capacity = 10 currentSize = 4list = □ i = 0 j = 2 currentMin = A currentMinIndex = 2

  49. Sort • Selection Sort capacity = 10 currentSize = 4list = □ i = 0 j = 3 currentMin = A currentMinIndex = 2

  50. Sort • Selection Sort capacity = 10 currentSize = 4list = □ i = 0 currentMin = A currentMinIndex = 3

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