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Stacks and Queues Processing Sequences of Elements SoftUni Team Technical Trainers Software University http://softuni.bg
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Table of Contents 1.Stack (LIFO – last in, first out) add(), pop(), peek(), toArray(), contains() and size() 2.Exercises on Stack 3.Queue (FIFO – first in, first out) add(), remove(), poll(), peek(), toArray(), contains() and size() 4.Exercises on Queue 5.Summary 2
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3 sli.do #8663 Questions
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4 Stack Overview 2 10 5
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5 Stack holds a stack of elements size() – the number of elements in the Stack peek() – checks the value of the last added element pop() – returns the last element and removes it from the stack add() – adds an element to the Stack toArray() – converts stack to array contains() – determines whether an element is in the stack Stack – LIFO Data Structure
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2105 6 add() – Adds an element on top of the Stack 0 size(): 1 2 3 Stack
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2 10 5 7 pop() – Returns the last element from the stack and removes it size(): 312 Stack
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1 5 8 size(): 5 peek() – Returns the last element from the stack, but does not remove it
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9 contains() – determines whether an element is present in the stack. Returns true if it is and false if it isn’t. toArray() – Converts the stack to an Array. Retains order of elements. contains(), toArray()
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01 2 5 3 210515 10 Stack – Overview of all operations size(): 5 -7 45 132 add() pop() peek() Stack
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Working with Stacks Live Demo! 01 2 5 3 210515 size(): 5 -7 45 132 push() pop() peek() Stack
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12 Queue Overview 2 10 5
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13 Queue holds a queue of elements: add() – adds an element at the end of the queue remove() – removes the first element and returns it (ex if empty) poll() – same as remove but returns null if queue is empty size() – returns the number of elements in the queue peek() – checks the value of the first element toArray() – converts the queue to an array contains() – checks whether an element is in the queue Queue – FIFO Data Structure
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-315121 3 2 10 4 14 add() – Adds an element to the front of the queue 5 size(): Queue
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4 2 3 15 5 size(): Queue -315121 remove() / poll() – Returns the first element from the queue and removes it
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15 2 16 size(): Queue 121 peek() – Returns the first element from the queue without removing it
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17 contains() - determines whether an element is present in the queue. Returns true if it is and false if it isn’t. toArray() - Converts the queue to an Array. Retains order of elements. contains(), toArray()
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5 -315 4 121 012 18 size(): Queue Queue – Overview of all operations 5 3 15 peek() remove() add()
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Queue Live Demo 5 -315 4 121 012 size(): Queue 5 3 15 peek() remove() add()
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Summary Stack – LIFO data structure The last element that is put in the stack is the first to come out Queue – FIFO data structure The first element that is put in the queue is the first to come out 20
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? ? ? ? ? ? ? ? ? Stacks, Queues https://softuni.bg/courses/java-fundamentals
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License This course (slides, examples, demos, videos, homework, etc.) is licensed under the "Creative Commons Attribution- NonCommercial-ShareAlike 4.0 International" licenseCreative Commons Attribution- NonCommercial-ShareAlike 4.0 International Attribution: this work may contain portions from "Fundamentals of Computer Programming with Java" book by Svetlin Nakov & Co. under CC-BY-SA licenseFundamentals of Computer Programming with JavaCC-BY-SA "C# Part I" course by Telerik Academy under CC-BY-NC-SA licenseC# Part ICC-BY-NC-SA "C# Part II" course by Telerik Academy under CC-BY-NC-SA licenseC# Part IICC-BY-NC-SA 22
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Free Trainings @ Software University Software University Foundation – softuni.orgsoftuni.org Software University – High-Quality Education, Profession and Job for Software Developers softuni.bg softuni.bg Software University @ Facebook facebook.com/SoftwareUniversity facebook.com/SoftwareUniversity Software University @ YouTube youtube.com/SoftwareUniversity youtube.com/SoftwareUniversity Software University Forums – forum.softuni.bgforum.softuni.bg
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