Explore
For Enterprise
Join for Free
Log In

HEC Paris
Develop an entrepreneurial mindset and drive innovation
Earn a high-quality career credential and credit towards a Master’s Degree in under 6 months
Rutgers University
Become a skilled supply chain leader in 4 months
Earn the Supply Chain Excellence MasterTrack™ Certificate from a top-ranked business school.

Explore todo o Coursera

Navegar
Os melhores cursos
For Enterprise
Entrar
Inscreva-se gratuitamente

Queues

Loading...

Algoritmos, Parte I

Universidade de Princeton

4.9 (5,972 classificações) | 480K alunos inscritos

Cadastre-se gratuitamente

This course covers the essential information that every serious programmer needs to know about algorithms and data structures, with emphasis on applications and scientific performance analysis of Java implementations. Part I covers elementary data structures, sorting, and searching algorithms. Part II focuses on graph- and string-processing algorithms. All the features of this course are available for free. It does not offer a certificate upon completion.

Visualizar o programa do curso

Habilidades que você aprenderá

Data Structure, Algorithms, Java Programming

Avaliações

4.9 (5,972 classificações)

5 stars
5,589 ratings
4 stars
325 ratings
3 stars
32 ratings
2 stars
9 ratings
1 star
17 ratings

RP

Jun 11, 2017

Incredible learning experience. Every programmer in industry should take this course if only to dispel the idea that with the advent of cloud computing exponential algorithms can still ruin your day!

KR

Dec 02, 2016

An amazing course which enables one to appreciate and analyze various algorithms used in various applications. Must take for anyone who wants to build a career in computer science or related fields.

Na lição

Stacks and Queues

We consider two fundamental data types for storing collections of objects: the stack and the queue. We implement each using either a singly-linked list or a resizing array. We introduce two advanced Java features—generics and iterators—that simplify client code. Finally, we consider various applications of stacks and queues ranging from parsing arithmetic expressions to simulating queueing systems.

Resizing Arrays9:56

Stack and Queue Applications (optional)13:24

Ministrado por

Kevin Wayne
Phillip Y. Goldman '86 Senior Lecturer
Robert Sedgewick
William O. Baker *39 Professor of Computer Science

Experimente o curso Gratuito

Transcrição

Okay, next we'll briefly consider queue implementations using the same basic underlying data structures. So here's the corresponding API for QueueOfStrings. Actually it's the same API as for stacks, just the names are different. Instead of push we have enqueue instead of pop we have dequeue. And the semantics is different, for enqueue we add an item say at the end of the queue, and for dequeue we remove an item from the beginning. It's as if you're waiting in line to buy a ticket. When you're enqueue you go at the end, and when the one that's been in there the longest is the one that comes off. So lets look at how we implement those, first using linked list and then arrays. So now our representation of a queue with a length list, we need to maintain two pointers, references. One, to the first item in the list and the other to the last item in the list. When we insert, we're going to add the item at the end of the list instead of at the beginning. And when we remove, we'll do the same, we'll take it off at the front. So here's the implementation of dequeue. It's identical to the code for pop for a stack. We save away the item, we delete the first node by advancing the reference and then we return the item, so identical. To add a note, or enqueue, add a new note to a linked-list. We want to put it at the end, so that will be the last one returned. So we, to add it at the end, so first thing we need to do is save a link, the last node. We're going to need that because we need to change it's reference from null to point to the new node. Then we'll create a new node for the end of the list. We'll populate its fields and then that old link will change that from null to a pointer to the new node. So again, just a few lines of code, [COUGH] that's basic linked-list processing. Actually years ago when we taught courses in algorithms and data structures, much of the course would be about this kind of pointer manipulation. But nowadays that's restricted to just a few implementations like stack and queue and a few other fundamental data structures. So we don't need so much any more general programs for manipulating linked-lists. We encapsulate them in basic data types like these. All right, so let's go back to our full implementation and this is just taking care of collecting the code from the previous slides. But also taking care of special cases when the queue is empty. To make sure that if the queue is empty after we move an item we gotta set last to null. Make sure that both first and last are always what we want them to be. So those are details that are easy to check. Okay, what about arrays? Well, we won't do the details, but it's not difficult to implement queues with resizing arrays as well. Not difficult, but a definitely tricky programming exercise that people are welcome to try. So we'll maintain two pointers, the first item in the queue and the tail, which is the position for the next item to appear. So for enqueue, you add a new item a tail. And for dequeue you remove an item for a head. And the trick is that once you get past the capacity, you have to reset back to zero. And so that's a little extra code, and then you have to add the resizing capability as well to implement the data structure the same as for stack. And we'll leave that as an exercise.

Explore nosso catálogo

Registre-se gratuitamente e obtenha recomendações, atualizações e ofertas personalizadas.

Os melhores cursos on-line

IA para todos
Introdução ao TensorFlow
Redes neurais e aprendizagem profunda
Algoritmos, parte 1
Algoritmos, parte 2
Aprendizagem Automática
Aprendizagem automática com Python
Aprendizagem automática usando o Sas Viya
Linguagem R
Introdução à programação com Matlab
Análise de dados com Python
Fundamentos da AWS: Going Cloud Native
Fundamentos da Google Cloud Platform
Engenharia de confiabilidade do site
Fale inglês profissionalmente
A ciência do bem-estar
Aprendendo a Aprender
Mercados Financeiros
Testes de hipóteses em saúde pública
Princípios da liderança no cotidiano

Principais programas de cursos integrados on-line

Aprendizagem profunda
Python para todosPython para todos
Ciência de Dados
Ciência de dados aplicada com Python
Fundamentos de negóciosFundamentos dos Negócios
Arquitetura com o Google Cloud Platform
Engenharia de dados em Google Cloud Platform
Excel para MySQL
Aprendizagem de máquina avançada
Matemática para aprendizagem automática
Carros autoguiáveis
Revolução do Blockchain para a empresa
Análises empresariaisAnálises Empresariais
Habilidades em Excel para negócios
Marketing digitalMarketing Digital
Análise estatística com R para saúde pública
Fundamentos da imunologia
Anatomia
Gestão da inovação e Design Thinking
Princípios da psicologia positiva

Certificados on-line

Suporte de TI do Google
Especialista em envolvimento de clientes da IBM
Ciência de dados da IBM
Gestão de projetos aplicados
Certificado Profissional IBM Applied AI
Aprendizagem automática para Análise
Visualização e análise de dados espaciais
Engenharia e Gerenciamento de Construção
Design instrucional

Programa de graduação on-line

Mestrado em ciência de dados
Bacharelado em ciência da computação
Graduação em ciência e engenharia da computação
Mestrado em aprendizagem automática
Graduação em negócios e MBA
Mestrado em engenharia elétrica
Mestrado em saúde pública
Mestrado em tecnologia da informação

Coursera

關於
管理團隊
工作機會
目錄
證書
MasterTrack™ 證書
學位
企業版
政府版
面向校園

Comunidade

學生
合作夥伴
開發者
Beta 測試人員
專業譯員
博客
技術博客

Mais

條款
隱私
幫助
內容訪問
媒體
聯繫我們
目錄
附屬公司

Baixar no Google Play

© 2020 Coursera Inc. Todos os direitos reservados.