Data structure and algorithms cấu trúc dữ liệu và thuật toán ch04 list

Data Structure and Algorithms [CO2003] Chapter - List Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Faculty of Computer Science and Engineering Hochiminh city University of Technology Contents Linear list concepts Array implementation Singly linked list Other linked lists Comparison of implementations of list Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Outcomes • L.O.2.1 - Depict the following concepts: (a) array list and linked list, including single link and double links, and multiple links; (b) stack; and (c) queue and circular queue • L.O.2.2 - Describe storage structures by using pseudocode for: (a) array list and linked list, including single link and double links, and multiple links; (b) stack; and (c) queue and circular queue • L.O.2.3 - List necessary methods supplied for list, stack, and queue, and describe them using pseudocode • L.O.2.4 - Implement list, stack, and queue using C/C++ Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Outcomes • L.O.2.5 - Use list, stack, and queue for problems in real-life, and choose an appropriate implementation type (array vs link) • L.O.2.6 - Analyze the complexity and develop experiment (program) to evaluate the efficiency of methods supplied for list, stack, and queue • L.O.8.4 - Develop recursive implementations for methods supplied for the following structures: list, tree, heap, searching, and graphs • L.O.1.2 - Analyze algorithms and use Big-O notation to characterize the computational complexity of algorithms composed by using the following control structures: sequence, branching, and iteration (not recursion) Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Linear list concepts Linear list concepts Definition A linear list is a data structure in which each element has a unique successor Example • Array • Linked list Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Linear list concepts Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Linear list concepts General list: • No restrictions on which operation can be used on the list • No restrictions on where data can be inserted/deleted • Unordered list (random list): Data are not in particular order • Ordered list: data are arranged according to a key Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Linear list concepts Restricted list: • Only some operations can be used on the list • Data can be inserted/deleted only at the ends of the list • Queue: FIFO (First-In-First-Out) • Stack: LIFO (Last-In-First-Out) Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 List ADT Definition A list of elements of type T is a finite sequence of elements of T Basic operations: • Construct a list, leaving it empty • Insert an element • Remove an element • Search an element • Retrieve an element • Traverse the list, performing a given operation on each element Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Linked list implementation in C++ How to use Linked List data structure? // int value ; L i n k e d L i s t ∗ m y L i s t = m y L i s t −>C l o n e ( ) ; c o u t G e t I t e m ( , v a l u e ) ; c o u t c o u n t ) return 0; Node ∗ newPtr , ∗ p P r e ; newPtr = new Node ( ) ; i f ( newPtr == NULL) return 0; newPtr−>d a t a = v a l u e ; i f ( head == NULL) { head = newPtr ; newPtr−>l i n k = NULL ; } e l s e i f ( p o s i t i o n == ) { newPtr−>l i n k = head ; head = newPtr ; } Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 72 / 83 Sample Solution: Insert else { // F i n d t h e p o s i t i o n p P r e = t h i s −>head ; o f pPre f o r ( i n t i = ; i < p o s i t i o n −1; i ++) p P r e = pPre−>l i n k ; // I n s e r t new node newPtr−>l i n k = pPre−>l i n k ; pPre−>l i n k = newPtr ; } t h i s −>c o u n t ++; return 1; } Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 73 / 83 Sample Solution: Delete template i n t L i n k e d L i s t : : D e l e t e I t e m ( i n t p o s i t i o n ) { i f ( p o s i t i o n < | | p o s i t i o n > t h i s −>c o u n t ) return 0; Node ∗ d l t P t r , ∗ p P r e ; i f ( p o s i t i o n == ) { d l t P t r = head ; head = head−>l i n k ; } else { p P r e= t h i s −>head ; f o r ( i n t i = ; i < p o s i t i o n −1; i ++) p P r e = pPre−>l i n k ; d l t P t r = pPre−>l i n k ; pPre−>l i n k = d l t P t r −>l i n k ; } delete dltPtr ; t h i s −>c o u n t −−; return 1; } Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 74 / 83 Sample Solution: Clone template L i n k e d L i s t ∗ L i n k e d L i s t : : C l o n e ( ) { L i n k e d L i s t ∗ r e s u l t = new L i n k e d L i s t ( ) ; Node∗ p = t h i s −>head ; w h i l e ( p != NULL) { r e s u l t −>I n s e r t L a s t ( p−>d a t a ) ; p = p−>l i n k ; } r e s u l t −>c o u n t = t h i s −>c o u n t ; return result ; } Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 75 / 83 Reverse a linked list Exercise template v o i d L i n k e d L i s t : : R e v e r s e ( ) { // } Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 76 / 83 Other linked lists Doubly Linked List Figure 4: Doubly Linked List allows going forward and backward node d a t a n e x t

p r e v i o u s

end node Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn list c u r r e n t

end l i s t Data Structure and Algorithms [CO2003] 77 / 83 Doubly Linked List Figure 5: Doubly Linked List allows going forward and backward Figure 6: Insert an element in Doubly Linked List Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 78 / 83 Circularly Linked List node d a t a l i n k

end node Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn list c u r r e n t

end l i s t Data Structure and Algorithms [CO2003] 79 / 83 Double circularly Linked List node d a t a n e x t

p r e v i o u s

end node Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn list c u r r e n t

end l i s t Data Structure and Algorithms [CO2003] 80 / 83 Comparison of implementations of list Arrays: Pros and Cons • Pros: • Access to an array element is fast since we can compute its location quickly • Cons: • If we want to insert or delete an element, we have to shift subsequent elements which slows our computation down • We need a large enough block of memory to hold our array Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 81 / 83 Linked Lists: Pros and Cons • Pros: • Inserting and deleting data does not require us to move/shift subsequent data elements • Cons: • If we want to access a specific element, we need to traverse the list from the head of the list to find it which can take longer than an array access Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 82 / 83 Comparison of implementations of list • Contiguous storage is generally preferable when: • • • • the entries are individually very small; the size of the list is known when the program is written; few insertions or deletions need to be made except at the end of the list; and random access is important • Linked storage proves superior when: • the entries are large; • the size of the list is not known in advance; and • flexibility is needed in inserting, deleting, and rearranging the entries Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] 83 / 83 ... nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Outcomes • L.O.2.1 - Depict the following concepts: (a) array list and linked list, including single link and double links, and multiple... Nguyen, PhD Contact: nddung@hcmut.edu.vn Data Structure and Algorithms [CO2003] / 83 Outcomes • L.O.2.5 - Use list, stack, and queue for problems in real-life, and choose an appropriate implementation... • Data can be inserted/deleted only at the ends of the list • Queue: FIFO (First-In-First-Out) • Stack: LIFO (Last-In-First-Out) Lecturer: Duc Dung Nguyen, PhD Contact: nddung@hcmut.edu.vn Data