| comments | difficulty | edit_url | tags | ||||
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true |
中等 |
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设计你的循环队列实现。 循环队列是一种线性数据结构，其操作表现基于 FIFO（先进先出）原则并且队尾被连接在队首之后以形成一个循环。它也被称为“环形缓冲器”。
循环队列的一个好处是我们可以利用这个队列之前用过的空间。在一个普通队列里，一旦一个队列满了，我们就不能插入下一个元素，即使在队列前面仍有空间。但是使用循环队列，我们能使用这些空间去存储新的值。
你的实现应该支持如下操作：
MyCircularQueue(k): 构造器，设置队列长度为 k 。Front: 从队首获取元素。如果队列为空，返回 -1 。Rear: 获取队尾元素。如果队列为空，返回 -1 。enQueue(value): 向循环队列插入一个元素。如果成功插入则返回真。deQueue(): 从循环队列中删除一个元素。如果成功删除则返回真。isEmpty(): 检查循环队列是否为空。isFull(): 检查循环队列是否已满。
示例：
MyCircularQueue circularQueue = new MyCircularQueue(3); // 设置长度为 3 circularQueue.enQueue(1); // 返回 true circularQueue.enQueue(2); // 返回 true circularQueue.enQueue(3); // 返回 true circularQueue.enQueue(4); // 返回 false，队列已满 circularQueue.Rear(); // 返回 3 circularQueue.isFull(); // 返回 true circularQueue.deQueue(); // 返回 true circularQueue.enQueue(4); // 返回 true circularQueue.Rear(); // 返回 4
提示：
- 所有的值都在 0 至 1000 的范围内；
- 操作数将在 1 至 1000 的范围内；
- 请不要使用内置的队列库。
我们可以使用一个长度为
调用 enQueue 方法时，我们首先检查队列是否已满，即
调用 deQueue 方法时，我们首先检查队列是否为空，即
调用 Front 方法时，我们首先检查队列是否为空，即
调用 Rear 方法时，我们首先检查队列是否为空，即
调用 isEmpty 方法时，我们只需判断
调用 isFull 方法时，我们只需判断
时间复杂度方面，以上操作的时间复杂度均为
class MyCircularQueue:
def __init__(self, k: int):
self.q = [0] * k
self.size = 0
self.capacity = k
self.front = 0
def enQueue(self, value: int) -> bool:
if self.isFull():
return False
self.q[(self.front + self.size) % self.capacity] = value
self.size += 1
return True
def deQueue(self) -> bool:
if self.isEmpty():
return False
self.front = (self.front + 1) % self.capacity
self.size -= 1
return True
def Front(self) -> int:
return -1 if self.isEmpty() else self.q[self.front]
def Rear(self) -> int:
if self.isEmpty():
return -1
return self.q[(self.front + self.size - 1) % self.capacity]
def isEmpty(self) -> bool:
return self.size == 0
def isFull(self) -> bool:
return self.size == self.capacity
# Your MyCircularQueue object will be instantiated and called as such:
# obj = MyCircularQueue(k)
# param_1 = obj.enQueue(value)
# param_2 = obj.deQueue()
# param_3 = obj.Front()
# param_4 = obj.Rear()
# param_5 = obj.isEmpty()
# param_6 = obj.isFull()class MyCircularQueue {
private int[] q;
private int front;
private int size;
private int capacity;
public MyCircularQueue(int k) {
q = new int[k];
capacity = k;
}
public boolean enQueue(int value) {
if (isFull()) {
return false;
}
int idx = (front + size) % capacity;
q[idx] = value;
++size;
return true;
}
public boolean deQueue() {
if (isEmpty()) {
return false;
}
front = (front + 1) % capacity;
--size;
return true;
}
public int Front() {
if (isEmpty()) {
return -1;
}
return q[front];
}
public int Rear() {
if (isEmpty()) {
return -1;
}
int idx = (front + size - 1) % capacity;
return q[idx];
}
public boolean isEmpty() {
return size == 0;
}
public boolean isFull() {
return size == capacity;
}
}
/**
* Your MyCircularQueue object will be instantiated and called as such:
* MyCircularQueue obj = new MyCircularQueue(k);
* boolean param_1 = obj.enQueue(value);
* boolean param_2 = obj.deQueue();
* int param_3 = obj.Front();
* int param_4 = obj.Rear();
* boolean param_5 = obj.isEmpty();
* boolean param_6 = obj.isFull();
*/class MyCircularQueue {
private:
int front;
int size;
int capacity;
vector<int> q;
public:
MyCircularQueue(int k) {
capacity = k;
q = vector<int>(k);
front = size = 0;
}
bool enQueue(int value) {
if (isFull()) return false;
int idx = (front + size) % capacity;
q[idx] = value;
++size;
return true;
}
bool deQueue() {
if (isEmpty()) return false;
front = (front + 1) % capacity;
--size;
return true;
}
int Front() {
if (isEmpty()) return -1;
return q[front];
}
int Rear() {
if (isEmpty()) return -1;
int idx = (front + size - 1) % capacity;
return q[idx];
}
bool isEmpty() {
return size == 0;
}
bool isFull() {
return size == capacity;
}
};
/**
* Your MyCircularQueue object will be instantiated and called as such:
* MyCircularQueue* obj = new MyCircularQueue(k);
* bool param_1 = obj->enQueue(value);
* bool param_2 = obj->deQueue();
* int param_3 = obj->Front();
* int param_4 = obj->Rear();
* bool param_5 = obj->isEmpty();
* bool param_6 = obj->isFull();
*/type MyCircularQueue struct {
front int
size int
capacity int
q []int
}
func Constructor(k int) MyCircularQueue {
q := make([]int, k)
return MyCircularQueue{0, 0, k, q}
}
func (this *MyCircularQueue) EnQueue(value int) bool {
if this.IsFull() {
return false
}
idx := (this.front + this.size) % this.capacity
this.q[idx] = value
this.size++
return true
}
func (this *MyCircularQueue) DeQueue() bool {
if this.IsEmpty() {
return false
}
this.front = (this.front + 1) % this.capacity
this.size--
return true
}
func (this *MyCircularQueue) Front() int {
if this.IsEmpty() {
return -1
}
return this.q[this.front]
}
func (this *MyCircularQueue) Rear() int {
if this.IsEmpty() {
return -1
}
idx := (this.front + this.size - 1) % this.capacity
return this.q[idx]
}
func (this *MyCircularQueue) IsEmpty() bool {
return this.size == 0
}
func (this *MyCircularQueue) IsFull() bool {
return this.size == this.capacity
}
/**
* Your MyCircularQueue object will be instantiated and called as such:
* obj := Constructor(k);
* param_1 := obj.EnQueue(value);
* param_2 := obj.DeQueue();
* param_3 := obj.Front();
* param_4 := obj.Rear();
* param_5 := obj.IsEmpty();
* param_6 := obj.IsFull();
*/class MyCircularQueue {
private queue: number[];
private left: number;
private right: number;
private capacity: number;
constructor(k: number) {
this.queue = new Array(k);
this.left = 0;
this.right = 0;
this.capacity = k;
}
enQueue(value: number): boolean {
if (this.isFull()) {
return false;
}
this.queue[this.right % this.capacity] = value;
this.right++;
return true;
}
deQueue(): boolean {
if (this.isEmpty()) {
return false;
}
this.left++;
return true;
}
Front(): number {
if (this.isEmpty()) {
return -1;
}
return this.queue[this.left % this.capacity];
}
Rear(): number {
if (this.isEmpty()) {
return -1;
}
return this.queue[(this.right - 1) % this.capacity];
}
isEmpty(): boolean {
return this.right - this.left === 0;
}
isFull(): boolean {
return this.right - this.left === this.capacity;
}
}
/**
* Your MyCircularQueue object will be instantiated and called as such:
* var obj = new MyCircularQueue(k)
* var param_1 = obj.enQueue(value)
* var param_2 = obj.deQueue()
* var param_3 = obj.Front()
* var param_4 = obj.Rear()
* var param_5 = obj.isEmpty()
* var param_6 = obj.isFull()
*/struct MyCircularQueue {
q: Vec<i32>,
size: usize,
capacity: usize,
front: usize,
}
impl MyCircularQueue {
fn new(k: i32) -> Self {
MyCircularQueue {
q: vec![0; k as usize],
size: 0,
capacity: k as usize,
front: 0,
}
}
fn en_queue(&mut self, value: i32) -> bool {
if self.is_full() {
return false;
}
let rear = (self.front + self.size) % self.capacity;
self.q[rear] = value;
self.size += 1;
true
}
fn de_queue(&mut self) -> bool {
if self.is_empty() {
return false;
}
self.front = (self.front + 1) % self.capacity;
self.size -= 1;
true
}
fn front(&self) -> i32 {
if self.is_empty() {
-1
} else {
self.q[self.front]
}
}
fn rear(&self) -> i32 {
if self.is_empty() {
-1
} else {
let rear = (self.front + self.size - 1) % self.capacity;
self.q[rear]
}
}
fn is_empty(&self) -> bool {
self.size == 0
}
fn is_full(&self) -> bool {
self.size == self.capacity
}
}