![1.1.2 Apply Stacks, Queues, Linked Lists
in programming
An Array Implementation
<<interface>>
Stack
+peek() :Object
+pop() :Object
+push(Object)
+size() :int
ArrayStack
-a :Object[]
-size :int
+ArrayStack(int)
+isEmpty():boolean
+peek() :Object
+pop() :Object
+push(Object)
+size() :int
-resize()](https://image.slidesharecdn.com/introductiondatastructure-171110150613/85/Introduction-data-structure-23-320.jpg)
![1.1.2 Apply Stacks, Queues, Linked Lists
in programming
An Array Implementation (refer to
ArrayStack.java)
• ArrayStack implementation uses a backing
array a[] to store the stack’s elements.
• Its other field is the integer size, which
keeps a count of the number of elements
in the stack.](https://image.slidesharecdn.com/introductiondatastructure-171110150613/85/Introduction-data-structure-25-320.jpg)
![1.1.2 Apply Stacks, Queues, Linked Lists
in programming
An Array Implementation (refer to
ArrayStack.java)
• The latter is called by push() when the
array is full.
• Its rebuild the array, doubling its size.
• This is done by declaring a temporary reference
aa[] to the array in line 35.](https://image.slidesharecdn.com/introductiondatastructure-171110150613/85/Introduction-data-structure-27-320.jpg)
![1.1.2 Apply Stacks, Queues, Linked Lists
in programming
An Array Implementation (refer to
ArrayStack.java)
• Redefining a[] as a new array with twice
the length in line 36.
• Using the arraycopy() method of the
system class to copy all the stack elements
from aa[] back to a[] in line 37.](https://image.slidesharecdn.com/introductiondatastructure-171110150613/85/Introduction-data-structure-28-320.jpg)
Introduction data structure
- 2. INTRODUCTION to course • Credit Hour: 3.0 • Contact Hour: 5 hours Tuesday (8.00 – 1.30 pm)
- 3. 1.0 Data Structures 1.1 Introduction to Data Structures
- 4. 1.1.1 Define Data Structures • A data structure is a scheme for organizing data in the memory of a computer. • A way of storing and organizing data in a computer so that it can be used efficiently
- 5. 1.1.1 Define Data Structures • Some of the more commonly used data structures include lists, arrays, stacks, queues, heaps, trees, and graphs. • The way in which the data is organized affects the performance of a program for different tasks.
- 6. 1.1.1 Define Data Structures • Computer programmers decide which data structures to use based on the nature of the data and the processes that need to be performed on that data.
- 7. Array Linked List Tree Queue Stack 1.1.1 Define Data Structures Types of data structures
- 8. 1.1.1 Define Data Structures The Need for Data Structures • Goal: to organize data • Criteria: to facilitate efficient storage of data retrieval of data manipulation of data
- 9. 1.1.1 Define Data Structures The Need for Data Structures • Design Issue: select and design appropriate data types (This is the main motivation to learn and underst and data structures)
- 10. 1.1.1 Define Data Structures Data Structure Operations • Traversing Accessing each data element exactly once so that certain items in the data may be processed • Searching Finding the location of the data element (key) in the structure • Insertion Adding a new data element to the structure
- 11. 1.1.1 Define Data Structures Data Structure Operations • Deletion Removing a data element from the structure • Sorting Arrange the data elements in a logical order (ascending/ descending) • Merging Combining data elements from two or more data structures into one
- 12. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack • Based on the principle of Last In First Out (LIFO) • Used extensively at every level of a modern computer system (compiler etc.)
- 13. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack • It is named stack as it behaves like a real-world stack. For example – a stack of books or a pile of plates, etc.
- 14. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Representation • The following diagram depicts a stack and its operations.
- 15. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Operations • Peek: If the stack is not empty, return its top element. • Pop: If the stack is not empty, delete and return its top element.
- 16. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Operations • Push: Add a given element to the top of the stack. • Size: Return the number of elements in the stack.
- 17. 1.1.2 Apply Stacks, Queues, Linked Lists in programming UML Diagram Translate into a Java interface Stack.java <<interface>> Stack +peek(): Object +pop(): Object +push(Object) +size(): int
- 18. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Example: … Stack crates = new ArrayStack(4); crates.push(“CARROT”); crates.push(“ORANGES”); crates.push(“RAISIN”); crates.pop(); crates.pop(); crates.push(“PEACH”); crates.push(“BANANAS”); crates.pop();
- 19. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Example: CARROT ORANGE CARROT ORANGE CARROT RAISIN ORANGE CARROT CARROT PEACH CARROT PEACH CARROT BANANAS
- 20. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Exercise: Stack stack= new ArrayStack(); stack.push(“Monday”); stack.push(“Tuesday”); stack.push(“Wednesday”); stack.pop(); stack.pop(); stack.push(“Thursday”); stack.push(“Friday”); stack.pop(); stack.push(“Saturday”); stack.push(“Sunday”); stack.pop(); stack.pop();
- 21. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Answer: Thursday Monday
- 22. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation • Several way to implement stack interface. • Simplest way is to use an ordinary array.
- 23. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation <<interface>> Stack +peek() :Object +pop() :Object +push(Object) +size() :int ArrayStack -a :Object[] -size :int +ArrayStack(int) +isEmpty():boolean +peek() :Object +pop() :Object +push(Object) +size() :int -resize()
- 24. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation Stack.java ArrayStack.java TestArrayStack.java
- 25. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation (refer to ArrayStack.java) • ArrayStack implementation uses a backing array a[] to store the stack’s elements. • Its other field is the integer size, which keeps a count of the number of elements in the stack.
- 26. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation (refer to ArrayStack.java) • In addition to the four methods required by the interface, the class also includes a public isEmpty() method and a private resize() method.
- 27. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation (refer to ArrayStack.java) • The latter is called by push() when the array is full. • Its rebuild the array, doubling its size. • This is done by declaring a temporary reference aa[] to the array in line 35.
- 28. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation (refer to ArrayStack.java) • Redefining a[] as a new array with twice the length in line 36. • Using the arraycopy() method of the system class to copy all the stack elements from aa[] back to a[] in line 37.
- 29. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation (refer to ArrayStack.java) • The peek() and pop() methods required that the stack be not empty. • This constrain enforce at line 14 and 19.
- 30. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation (refer to ArrayStack.java) • Note at line 21 the pop() method resets to null the array element that references the object being remove from the stack.
- 31. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Array Implementation (refer to ArrayStack.java) • This prevents an unreachable reference from being maintain. • This class is tested in TestArrayStack.java
- 32. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue • is a data structure that implements the first-in-first-out (FIFO) protocol. • The only access point in the structure are at its ends where the elements are inserted and removed.
- 33. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue • Insertions are always made at the back of the queue. • Removals are always made at the front.
- 34. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue • The queue data structure abstracts the notion of an ordinary waiting line such as a line of people waiting to purchase admission tickets.
- 35. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue Operations • Add: Insert a given element at the back of the queue. • First: If the queue is not empty, return the element that is at the front of the queue.
- 36. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue Operations • Remove: If the queue is not empty, delete and return the element that is at the front of the queue. • Size: Return the number of elements in the queue.
- 37. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue Operations Translate into a Java interface Queue.java <<interface>> Queue +add(object) +first(): object +remove(): object +size(): int
- 38. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue Example: … Queue queue = new ArrayQueue(); queue.add(“CARROT”); queue.add(“ORANGES”); queue.add(“RAISIN”); queue.remove(); queue.remove(); queue.add(“PEACH”); queue.add(“BANANAS”); queue.remove(); queue.add(“DURIAN”); queue.add(“GRAPES”); queue.remove(); queue.remove();
- 39. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Example: CARROT ORANGECARROT RAISINORANGECARROT RAISINORANGE RAISIN PEACHRAISIN BANANASPEACHRAISIN BANANASPEACH DURIANBANANASPEACH DURIANBANANASPEACH GRAPES
- 40. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Stack Example: DURIANBANANAS GRAPES DURIAN GRAPES
- 41. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue Exercise: … Queue queue = new ArrayQueue(); queue.add(“MONDAY”); queue.add(“TUESDAY”); queue.add(“SUNDAY”); queue.remove(); queue.remove(); queue.add(“WEDNESDAY”); queue.add(“SATURDAY”); queue.remove(); queue.remove(); queue.add(“THURSDAY”); queue.add(“FRIDAY”); queue.remove(); queue.remove();
- 42. 1.1.2 Apply Stacks, Queues, Linked Lists in programming Queue Answer: Friday
- 43. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Queue Implementation • Several way to implement queue interface. • Simplest way is to use an array as we did with the ArrayStack implementation of the Stack interface.
- 44. 1.1.2 Apply Stacks, Queues, Linked Lists in programming An Queue Implementation • The simplest alternative way to an array implementation is a linked implementation.