mirror of
https://github.com/krahets/hello-algo.git
synced 2024-12-26 12:36:30 +08:00
78 lines
2.2 KiB
Markdown
78 lines
2.2 KiB
Markdown
# 双向队列
|
||
|
||
对于队列，我们只能在头部删除或在尾部添加元素，而「双向队列 Deque」更加灵活，在其头部和尾部都能执行元素添加或删除操作。
|
||
|
||
|
||
|
||
<p align="center"> Fig. 双向队列的操作 </p>
|
||
|
||
## 双向队列常用操作
|
||
|
||
双向队列的常用操作见下表，方法名需根据编程语言设定来具体确定。
|
||
|
||
<p align="center"> Table. 双向队列的常用操作 </p>
|
||
|
||
<div class="center-table" markdown>
|
||
|
||
| 方法 | 描述 |
|
||
| ------------ | ---------------- |
|
||
| offerFirst() | 将元素添加至队首 |
|
||
| offerLast() | 将元素添加至队尾 |
|
||
| pollFirst() | 删除队首元素 |
|
||
| pollLast() | 删除队尾元素 |
|
||
| peekFirst() | 访问队首元素 |
|
||
| peekLast() | 访问队尾元素 |
|
||
| size() | 获取队列的长度 |
|
||
| isEmpty() | 判断队列是否为空 |
|
||
|
||
</div>
|
||
|
||
相同地，我们可以直接使用编程语言实现好的双向队列类。
|
||
|
||
=== "Java"
|
||
|
||
```java title="deque.java"
|
||
/* 初始化双向队列 */
|
||
Deque<Integer> deque = new LinkedList<>();
|
||
|
||
/* 元素入队 */
|
||
deque.offerLast(2);
|
||
deque.offerLast(5);
|
||
deque.offerLast(4);
|
||
deque.offerFirst(3);
|
||
deque.offerFirst(1);
|
||
System.out.println("队列 deque = " + deque);
|
||
|
||
/* 访问队首元素 */
|
||
int peekFirst = deque.peekFirst();
|
||
System.out.println("队首元素 peekFirst = " + peekFirst);
|
||
int peekLast = deque.peekLast();
|
||
System.out.println("队尾元素 peekLast = " + peekLast);
|
||
|
||
/* 元素出队 */
|
||
int pollFirst = deque.pollFirst();
|
||
System.out.println("队首出队元素 pollFirst = " + pollFirst +
|
||
"，队首出队后 deque = " + deque);
|
||
int pollLast = deque.pollLast();
|
||
System.out.println("队尾出队元素 pollLast = " + pollLast +
|
||
"，队尾出队后 deque = " + deque);
|
||
|
||
/* 获取队列的长度 */
|
||
int size = deque.size();
|
||
System.out.println("队列长度 size = " + size);
|
||
|
||
/* 判断队列是否为空 */
|
||
boolean isEmpty = deque.isEmpty();
|
||
```
|
||
|
||
=== "C++"
|
||
|
||
```cpp title="deque.cpp"
|
||
|
||
```
|
||
|
||
=== "Python"
|
||
|
||
```python title="deque.py"
|
||
|
||
```
|