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Lists

Lists. List L = x 0 x 1 x 2 x 3 … x n-1 n = # elements If a list is ordered than the key of x i-1 <= the key of x i for all i where 0 < i < n. The sort symbol <= can be replaced by >= or any other function that determines ordering in the keys.

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Lists

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  1. Lists List L = x0 x1 x2 x3 … xn-1 n = # elements If a list is ordered than the key of xi-1 <= the key of xi for all i where 0 < i < n. The sort symbol <= can be replaced by >= or any other function that determines ordering in the keys. An unordered list does not have this restriction. Functions: access(L, i) returns xi length(L) returns n concat(L1, L2) returns a new list with L2 concatenated on to L1 createEmptyList() returns a newly created empty list isEmptyList(L) returns true if L is empty and false if it is not searchFor(L, key) returns i where the key of xi = key remove(L, i) returns a list with xi removed; the old xi+1 is now xi, etc. inserti(L, i, x) returns a list with x inserted as xi; the old xi is now xi+1, etc. insert(L, x) returns a list with x added to L sort(L) returns the list in sorted order

  2. A Node With Pointer NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95

  3. Homework 1 • Describe how to use a set of nodes with pointers (as described in class) to implement a variable length unordered list. • Determine how to do the following functions: access, length, concat, createEmptyList, isEmptyList, searchFor, remove, inserti, and insert. • How would any of these functions change if the list was to be ordered?

  4. NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 Linked List head when we pass a list in as a parameter we pass in the head a pointer pointing to null indicates the end of the list null is a node pointer which is part of the node, we’ll call it next

  5. NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 Linked List with Tail tail head null

  6. NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 Linked List head when we pass a list in as a parameter we pass in the head a pointer pointing to null indicates the end of the list null is a node pointer which is part of the node, we’ll call it next

  7. createEmptyList() Declare a pointer to type node called head n = 0 head null

  8. isEmptyList(L) if head == null return true else return false

  9. isEmptyList(L) return head == null

  10. access(L, i) declare a pointer temp if i < 0 or i >= n return null temp = head for j = 0; j < i; j++ temp = temp.next return temp

  11. length(L) int count = 0 temp = head while temp != null count = count + 1 temp = temp.next return count

  12. length(L) return n

  13. searchFor(L, key) int count = 0 temp = head while temp != null if temp.key = key return count count = count + 1 temp = temp.next return -1

  14. insert(L, x) loop until temp.next == null then temp.next = x n = n + 1

  15. insert(L, x) x.next = head head = x n = n + 1

  16. concat(L1, L2) if head1 == null head1 = head2 else temp = head1 while temp.next != null temp = temp.next temp.next = head2 n1 = n1 +n2 return head1

  17. NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 remove(L, i) p1 p2 head null p1 p2 head null p1.next = p2.next P2.next = null

  18. p1 p2 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 head null inserti(L, i, x) p1 p2 head null p2.next = p1.next p1.next = p2

  19. NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 search-remove p head null

  20. NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 Doubly Linked List tail p head null null Two pointers per node: next prev

  21. NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 NameLast: Smart FirstName: Joe StudentNumber: 8 SSN: 123-34-1112 Grade: 95 Circular Linked List p

  22. Stacks Stack S = x0 x1 x2 x3 … xn-1 n = # elements A stack is a list but the nodes are only accessed last-in-first-out (LIFO). Functions: createEmptyStack() returns a newly created empty stack top(S) returns the last node of S pop(S) returns and removes the last node of S push(S, x) returns a S with x added as the last element isEmptyStack(S) returns true if S is empty and false if it is not

  23. Homework 2 • Describe how to implement a stack using an array (assume it will never have more than 100 elements). • Do the five stack functions. • Describe how to implement a stack using an set of nodes (this stack will have no number of element limit). • Do the five stack functions.

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