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Deque(덱) : Double Ended Queue

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Deque(덱)이란?

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\"Deque(덱)\"\n출처1

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Deque(덱) 구현

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Deque(덱) 구현 시 다음의 메소드들은 꼭 필요하다.

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  1. push_front(data) = 앞에 삽입 : data node를 deque(덱)의 제일 앞에 push(삽입)한다.
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  2. push_back(data) = 뒤에 삽입 : data node를 deque(덱)의 제일 뒤에 push(삽입)한다.
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  3. pop_front() = 선두 삭제 : deque(덱)의 front(head) node를 pop(삭제)하고, 가장 앞에 있는 node를 front(head) node로 지정한다.
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  4. pop_back() = 후미 삭제 : deque(덱)의 rear(tail) node를 pop(삭제)하고, 가장 뒤에 있는 node를 rear(tail) node로 지정한다.
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추가적으로 deque(덱)이 비었는지 차있는지 확인해주는 isempty()메소드와, front(head) & rear(tail) node의 data를 반환해주는 getfront() & get_rear()메소드들과 같이, 상황에 맞게 만들어진 사용자 정의 메소드들이 많이 쓰인다.

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Deque(덱) 구현 코드 (C++)

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#include <iostream>\n#include <string>\n\ntemplate <typename T>\nstruct Node {\n\tT data;\n\tstruct Node *front;\n\tstruct Node *rear;\n};\n\ntemplate <typename T>\nclass Deque {\nprivate:\n\tNode<T> *head;\n\tNode<T> *tail;\n\tint size;\n\t\npublic:\n\tDeque() : head(nullptr), tail(nullptr), size(0) {}\n\t~Deque() {\n\t\tif (this->head == nullptr)\n\t\t\treturn;\n\t\t\n\t\tNode<T> *cur = this->tail;\n\t\t\n\t\twhile (cur != nullptr) {\n\t\t\tcur = cur->front;\n\t\t\tdelete this->tail;\n\t\t\tthis->tail = cur;\n\t\t}\n\t\t\n\t\tthis->head = this->tail;\n\t}\n\t\n\tint get_size() {\n\t\treturn this->size;\n\t}\n\t\n\tbool is_empty() {\n\t\treturn this->head == nullptr ? true : false;\n\t}\n\t\n\tvoid push_front(T value) {\n\t\tNode<T> *node = new Node<T>;\n\t\tnode->data = value;\n\t\tnode->front = nullptr;\n\t\tnode->rear = nullptr;\n\t\t\n\t\tif (is_empty()) // first push.\n\t\t\tthis->tail = node;\n\t\telse {\n\t\t\tnode->rear = this->head;\n\t\t\tthis->head->front = node;\n\t\t}\n\t\t\n\t\tthis->head = node;\n\t\t++size;\n\t}\n\t\n\tvoid push_back(T value) {\n\t\tNode<T> *node = new Node<T>;\n\t\tnode->data = value;\n\t\tnode->front = nullptr;\n\t\tnode->rear = nullptr;\n\t\t\n\t\tif (is_empty()) // first push.\n\t\t\tthis->head = node;\n\t\telse {\n\t\t\tnode->front = this->tail;\n\t\t\tthis->tail->rear = node;\n\t\t}\n\t\t\n\t\tthis->tail = node;\n\t\t++size;\n\t}\n\t\n\tT pop_front() {\n\t\tif (is_empty()) // empty deque.\n\t\t\treturn -1; // T type에 맞는 error code return.\n\t\telse {\n\t\t\tint pop_val = this->head->data;\n\t\t\t\n\t\t\tif (this->head == this->tail) { // deque with 1 element.\n\t\t\t\tdelete this->head;\n\t\t\t\tthis->head = this->tail = nullptr;\n\t\t\t}\n\t\t\telse { // deque with more than 2 elements.\n\t\t\t\tNode<T> *node = new Node<T>;\n\t\t\t\t\n\t\t\t\tnode = this->head->rear;\n\t\t\t\t\n\t\t\t\tdelete this->head;\n\t\t\t\t\n\t\t\t\tthis->head = node;\n\t\t\t\tthis->head->front = nullptr;\n\t\t\t}\n\t\t\t\n\t\t\t--size;\n\t\t\treturn pop_val;\n\t\t}\n\t}\n\t\n\tT pop_back() {\n\t\tif (is_empty()) // empty deque.\n\t\t\treturn -1; // T type에 맞는 error code return.\n\t\telse {\n\t\t\tint pop_val = this->tail->data;\n\t\t\t\n\t\t\tif (this->head == this->tail) { // deque with 1 element.\n\t\t\t\tdelete this->head;\n\t\t\t\tthis->head = this->tail = nullptr;\n\t\t\t}\n\t\t\telse { // deque with more than 2 elements.\n\t\t\t\tNode<T> *node = new Node<T>;\n\t\t\t\t\n\t\t\t\tnode = this->tail->front;\n\t\t\t\t\n\t\t\t\tdelete this->tail;\n\t\t\t\t\n\t\t\t\tthis->tail = node;\n\t\t\t\tthis->tail->rear = nullptr;\n\t\t\t}\n\t\t\t\n\t\t\t--size;\n\t\t\treturn pop_val;\n\t\t}\n\t}\n\t\n\tT get_head() {\n\t\tif (is_empty()) // empty deque.\n\t\t\treturn -1; // T type에 맞는 error code return.\n\t\telse\n\t\t\treturn this->head->data;\n\t}\n\t\n\tT get_tail() {\n\t\tif (is_empty()) // empty deque.\n\t\t\treturn -1; // T type에 맞는 error code return.\n\t\telse\n\t\t\treturn this->tail->data;\n\t}\n};\n\nint main() {\n\tstd::ios::sync_with_stdio(false);\n\tstd::cin.tie(NULL); \n\tstd::cout.tie(NULL);\n\t\n\tDeque<int> deque;\n\t\n\tdeque.push_front(2);\n\tstd::cout << deque << std::endl;\n\t\n\tdeque.push_back(1);\n\tstd::cout << deque << std::endl;\n\t\n\tstd::cout << \"pop back : \" << deque.pop_back() << std::endl;\n\tstd::cout << deque << std::endl;\n\t\n\tstd::cout << \"pop front : \" << deque.pop_front() << std::endl;\n\tstd::cout << deque << std::endl;\n\t\n\treturn 0;\n}
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    https://commons.wikimedia.org/wiki/File:Deque.gif

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","fields":{"tagSlugs":["/tags/data-structure/"],"slug":"/posts/data_structures/double_ended_queue/"},"frontmatter":{"title":"[자료구조] Deque(덱) : Double Ended Queue","tags":["Data Structure"],"date":"2020-04-09","description":"Deque(덱) : Double Ended Queue에 대해 알아보자."}}},"pageContext":{"slug":"/posts/data_structures/double_ended_queue/"}}