设计循环双端队列
- https://leetcode.cn/problems/design-circular-deque/description/
描述
-
设计实现双端队列。
-
实现
MyCircularDeque类:MyCircularDeque(int k)：构造函数,双端队列最大为 k 。boolean insertFront()：将一个元素添加到双端队列头部。 如果操作成功返回 true ，否则返回 false 。boolean insertLast()：将一个元素添加到双端队列尾部。如果操作成功返回 true ，否则返回 false 。boolean deleteFront()：从双端队列头部删除一个元素。 如果操作成功返回 true ，否则返回 false 。boolean deleteLast()：从双端队列尾部删除一个元素。如果操作成功返回 true ，否则返回 false 。int getFront())：从双端队列头部获得一个元素。如果双端队列为空，返回 -1 。int getRear()：获得双端队列的最后一个元素。 如果双端队列为空，返回 -1 。boolean isEmpty()：若双端队列为空，则返回 true ，否则返回 false 。boolean isFull()：若双端队列满了，则返回 true ，否则返回 false 。
示例 1：
输入
["MyCircularDeque", "insertLast", "insertLast", "insertFront", "insertFront", "getRear", "isFull", "deleteLast", "insertFront", "getFront"]
[[3], [1], [2], [3], [4], [], [], [], [4], []]
输出
[null, true, true, true, false, 2, true, true, true, 4]
解释
MyCircularDeque circularDeque = new MycircularDeque(3); // 设置容量大小为3
circularDeque.insertLast(1); // 返回 true
circularDeque.insertLast(2); // 返回 true
circularDeque.insertFront(3); // 返回 true
circularDeque.insertFront(4); // 已经满了，返回 false
circularDeque.getRear(); // 返回 2
circularDeque.isFull(); // 返回 true
circularDeque.deleteLast(); // 返回 true
circularDeque.insertFront(4); // 返回 true
circularDeque.getFront(); // 返回 4
提示：
- 1 <= k <= 1000
- 0 <= value <= 1000
- insertFront, insertLast, deleteFront, deleteLast, getFront, getRear, isEmpty, isFull 调用次数不大于 2000 次
Typescript 版算法实现
1 ) 方案1：数组
class MyCircularDeque {
private capacity: number;
private rear: number;
private front: number;
private elements: number[];
constructor(k: number) {
this.capacity = k + 1; // 使用 k+1 来区分满和空的情况
this.rear = 0;
this.front = 0;
this.elements = new Array<number>(this.capacity).fill(0);
}
insertFront(value: number): boolean {
if (this.isFull()) {
return false;
}
this.front = (this.front - 1 + this.capacity) % this.capacity;
this.elements[this.front] = value;
return true;
}
insertLast(value: number): boolean {
if (this.isFull()) {
return false;
}
this.elements[this.rear] = value;
this.rear = (this.rear + 1) % this.capacity;
return true;
}
deleteFront(): boolean {
if (this.isEmpty()) {
return false;
}
this.front = (this.front + 1) % this.capacity;
return true;
}
deleteLast(): boolean {
if (this.isEmpty()) {
return false;
}
this.rear = (this.rear - 1 + this.capacity) % this.capacity;
return true;
}
getFront(): number {
if (this.isEmpty()) {
return -1;
}
return this.elements[this.front];
}
getRear(): number {
if (this.isEmpty()) {
return -1;
}
return this.elements[(this.rear - 1 + this.capacity) % this.capacity];
}
isEmpty(): boolean {
return this.rear === this.front;
}
isFull(): boolean {
return (this.rear + 1) % this.capacity === this.front;
}
}
/**
* Your MyCircularDeque object will be instantiated and called as such:
* var obj = new MyCircularDeque(k)
* var param_1 = obj.insertFront(value)
* var param_2 = obj.insertLast(value)
* var param_3 = obj.deleteFront()
* var param_4 = obj.deleteLast()
* var param_5 = obj.getFront()
* var param_6 = obj.getRear()
* var param_7 = obj.isEmpty()
* var param_8 = obj.isFull()
*/
2 ) 方案2：链表
// 定义节点结构
class Node {
prev: Node | null = null;
next: Node | null = null;
val: number;
constructor(value: number) {
this.val = value;
}
}
class MyCircularDeque {
head: Node | null = null;
tail: Node | null = null;
capacity: number;
size: number = 0;
constructor(k: number) {
this.capacity = k;
}
// 在队列前端插入元素
insertFront(value: number): boolean {
if (this.isFull()) {
return false;
}
const newNode = new Node(value);
if (this.isEmpty()) {
this.head = newNode;
this.tail = newNode;
} else {
newNode.next = this.head;
if (this.head) {
this.head.prev = newNode;
}
this.head = newNode;
}
this.size++;
return true;
}
// 在队列末端插入元素
insertLast(value: number): boolean {
if (this.isFull()) {
return false;
}
const newNode = new Node(value);
if (this.isEmpty()) {
this.head = newNode;
this.tail = newNode;
} else {
if (this.tail) {
this.tail.next = newNode;
newNode.prev = this.tail;
}
this.tail = newNode;
}
this.size++;
return true;
}
// 从队列前端删除元素
deleteFront(): boolean {
if (this.isEmpty()) {
return false;
}
if (this.head) {
this.head = this.head.next;
if (this.head) {
this.head.prev = null;
} else {
this.tail = null; // 如果删除后队列为空，更新尾指针
}
}
this.size--;
return true;
}
// 从队列末端删除元素
deleteLast(): boolean {
if (this.isEmpty()) {
return false;
}
if (this.tail) {
this.tail = this.tail.prev;
if (this.tail) {
this.tail.next = null;
} else {
this.head = null; // 如果删除后队列为空，更新头指针
}
}
this.size--;
return true;
}
// 获取队列前端的元素
getFront(): number {
if (this.isEmpty()) {
return -1;
}
return this.head?.val ?? -1;
}
// 获取队列末端的元素
getRear(): number {
if (this.isEmpty()) {
return -1;
}
return this.tail?.val ?? -1;
}
// 检查队列是否为空
isEmpty(): boolean {
return this.size === 0;
}
// 检查队列是否已满
isFull(): boolean {
return this.size === this.capacity;
}
}
/**
* Your MyCircularDeque object will be instantiated and called as such:
* var obj = new MyCircularDeque(k)
* var param_1 = obj.insertFront(value)
* var param_2 = obj.insertLast(value)
* var param_3 = obj.deleteFront()
* var param_4 = obj.deleteLast()
* var param_5 = obj.getFront()
* var param_6 = obj.getRear()
* var param_7 = obj.isEmpty()
* var param_8 = obj.isFull()
*/
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