641。設計圓形雙端隊列
難度：中
主題：陣列、鍊錶、設計、隊列
設計循環雙端隊列（deque）的實作。
實作 MyCircularDeque 類別：
範例1：
["MyCircularDeque", "insertLast", "insertLast", "insertFront", "insertFront", "getRear", "isFull", "deleteLast", "insertFront", "getFront"] [[3], [1], [2], [3], [4], [], [], [], [4], []]
[null, true, true, true, false, 2, true, true, true, 4]
MyCircularDeque myCircularDeque = new MyCircularDeque(3); myCircularDeque.insertLast(1); // return True myCircularDeque.insertLast(2); // return True myCircularDeque.insertFront(3); // return True myCircularDeque.insertFront(4); // return False, the queue is full. myCircularDeque.getRear(); // return 2 myCircularDeque.isFull(); // return True myCircularDeque.deleteLast(); // return True myCircularDeque.insertFront(4); // return True myCircularDeque.getFront(); // return 4
約束：
解：
我們可以使用陣列來表示雙端隊列結構。我們將維護一個頭指針和尾指針，幫助我們追蹤雙端隊列的前部和後部，並在必要時環繞以實現循環行為。
讓我們用 PHP 實作這個解：641。設計圓形雙端隊列
這是 MyCircularDeque 類別的逐步解決方案：
<?php
class MyCircularDeque {
/**
* @var array
*/
private $deque;
/**
* @var int
*/
private $maxSize;
/**
* @var int
*/
private $front;
/**
* @var int
*/
private $rear;
/**
* @var int
*/
private $size;
/**
* Initialize your data structure here. Set the size of the deque to be k.
*
* @param Integer $k
*/
function __construct($k) {
...
...
...
/**
* go to ./solution.php
*/
}
/**
* Adds an item at the front of Deque. Return true if the operation is successful.
*
* @param Integer $value
* @return Boolean
*/
function insertFront($value) {
...
...
...
/**
* go to ./solution.php
*/
}
/**
* Adds an item at the rear of Deque. Return true if the operation is successful.
*
* @param Integer $value
* @return Boolean
*/
function insertLast($value) {
...
...
...
/**
* go to ./solution.php
*/
}
/**
* Deletes an item from the front of Deque. Return true if the operation is successful.
*
* @return Boolean
*/
function deleteFront() {
...
...
...
/**
* go to ./solution.php
*/
}
/**
* Deletes an item from the rear of Deque. Return true if the operation is successful.
*
* @return Boolean
*/
function deleteLast() {
...
...
...
/**
* go to ./solution.php
*/
}
/**
* Get the front item from the deque. If the deque is empty, return -1.
*
* @return Integer
*/
function getFront() {
...
...
...
/**
* go to ./solution.php
*/
}
/**
* Get the last item from the deque. If the deque is empty, return -1.
*
* @return Integer
*/
function getRear() {
...
...
...
/**
* go to ./solution.php
*/
}
/**
* Checks whether the deque is empty or not.
*
* @return Boolean
*/
function isEmpty() {
...
...
...
/**
* go to ./solution.php
*/
}
/**
* Checks whether the deque is full or not.
*
* @return Boolean
*/
function isFull() {
...
...
...
/**
* go to ./solution.php
*/
}
}
/**
* Your MyCircularDeque object will be instantiated and called as such:
* $obj = MyCircularDeque($k);
* $ret_1 = $obj->insertFront($value);
* $ret_2 = $obj->insertLast($value);
* $ret_3 = $obj->deleteFront();
* $ret_4 = $obj->deleteLast();
* $ret_5 = $obj->getFront();
* $ret_6 = $obj->getRear();
* $ret_7 = $obj->isEmpty();
* $ret_8 = $obj->isFull();
*/
?>
初始化:
insertFront($value):
insertLast($value):
deleteFront():
deleteLast():
getFront():
getRear():
isEmpty():
isFull():
$myCircularDeque = new MyCircularDeque(3); // Initialize deque with size 3 $myCircularDeque->insertLast(1); // return true $myCircularDeque->insertLast(2); // return true $myCircularDeque->insertFront(3); // return true $myCircularDeque->insertFront(4); // return false, deque is full echo $myCircularDeque->getRear(); // return 2 echo $myCircularDeque->isFull(); // return true $myCircularDeque->deleteLast(); // return true $myCircularDeque->insertFront(4); // return true echo $myCircularDeque->getFront(); // return 4
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