Winter 2016 COMP-250: Introduction to Computer Science. Lecture 6, January 28, 2016

Transcription

1 Winter 2016 COMP-250: Introduction to Computer Science Lecture 6, January 28, 2016

2 Java Generics element next _,

3 Java Generics

4 Java Generics

5 (Doubly) Linked List

6 (Doubly) Linked List Node element next prev 9,,

7 head tail size,,4,,,,,,,,

8 head tail size,,4,,,,,,,,

9 head tail size,,4,,,,,,,,

10 head tail size,,4,,,,,,,,

11 head tail size,,4,,,,,,,,

12 node head tail size,,4,,,,,,,,

13 node head tail size,,4,,,,,,,,

14 node head tail size,,4,,,,,,,,

15 node head tail size,,4,,,,,,,,

16 node head tail size,,4,,,,,,,,

17 node head tail size,,4 3,,,,,,,,

18 node head tail size,,4 3,,,,,,,,

19 node head tail size,,4 3,,,,,,,,

20 node head tail size,,4 3,,,,,,,,

21 node head tail size,,4 3,,,,,,,,

22 node head tail size,,4,,,,,,,,

23 node head tail size,,4,,,,,,,,

24 node head tail size,,4,,,,,,,,

25 dummy dummy. Head Tail size,,2,,,,,,,,

26 node head tail size,,2,,,,,,,,

27 node head tail size,,2,,,,,,,,

28 node head tail size,,2,,,,,,,,

29 node head tail size,,2,,,,,,,,

30 node head tail size,,2,,,,,,,,

31 node head tail size,,2 1,,,,,,,,

32 node head tail size,,2 1,,,,,,,,

33 node head tail size,,2 1,,,,,,,,

34 node head tail size,,2 1,,,,,,,,

35 node head tail size,,2 1,,,,,,,,

36 Array vs Linked List

37 Linked Lists as ADT (Abstract Data Type)

38 Linked List operations

39 Java LinkedList implemented as doubly linked list (with dummies) Node class is private dummy dummy. Head Tail size,,2,,,,,,,,

40 Java LinkedList,,2,,,,,,,,

41 Java LinkedList }expensive,,2,,,,,,,,

42 Java LinkedList Time(n) is Ω(n 2 ),,2,,,,,,,,

43 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,,

44 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,, element

45 Java ArrayList when new space is needed doubles the array size. array size cap. element,4,4,,,,,,,,,,

46 Java ArrayList smaller array is copied into bigger array. array size cap. element,4,4,,,,,,,,,,

47 Java ArrayList new element added to new array array size cap.,4,8 element,,,,,,,

48 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,8,,,,,,,

49 Cost?

50 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,,,,,,,,,

51 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation Extra cost of 2k+1 new steps only if 2k steps already spent before! array size cap.,4,4,,,,,,,,,,

52 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation Extra cost of 2k+1 new steps only if 2k steps already spent before! array size cap. Cost is amortized constant time!,4,4,,,,,,,,,,

53 Java ArrayList ,,,,,,,,,,,

54 Java ArrayList To build an array of 2 k elements you need 2 k+1-1 steps! ,,,,,,,,,,,

55 Java ArrayList To build an array of 2 k elements Cost is amortized constant time! you need 2 k+1-1 steps! ,,,,,,,,,,,

56 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,, element

57 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,, element

58 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4 element,,, Cost is constant!

59 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,, get(2)

60 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,, get(2) Cost is constant!

61 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,, get(2) Cost is constant!

62 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,, get(2) Cost is constant!

63 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,4,,, get(2) Cost is constant!

64 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation array size cap.,4,8,,,,,,,

65 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8,,,,,,,

66 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8,,,,,,,

67 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8,,,,,,,

68 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8,,,,,,,

69 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8,,,,,,,

70 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8,,,,,,,

71 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8,,,,,,,

72 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8 5,,,,,,,

73 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8 5 Cost is linear!,,,,,,,

74 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8 5 Cost is linear! Same for Remove!,,,,,,,

75 Java ArrayList implementation using arrays of growing sizes cannot access using a[i] notation element array size cap.,4,8 5 Cost is linear! Same for Remove!,,,,,,,

76 LinkedList vs ArrayList

77 Winter 2016 COMP-250: Introduction to Computer Science Lecture 6, January 28, 2016