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 <= 10000 <= value <= 1000insertFront,insertLast,deleteFront,deleteLast,getFront,getRear,isEmpty,isFull调用次数不大于2000次
方法一：数组
利用循环数组，实现循环双端队列。
基本元素有：
- front：队头元素的下标
- size：队列中元素的个数
- capacity：队列的容量
- q：循环数组，存储队列中的元素
时间复杂度
class MyCircularDeque:
def __init__(self, k: int):
"""
Initialize your data structure here. Set the size of the deque to be k.
"""
self.q = [0] * k
self.front = 0
self.size = 0
self.capacity = k
def insertFront(self, value: int) -> bool:
"""
Adds an item at the front of Deque. Return true if the operation is successful.
"""
if self.isFull():
return False
if not self.isEmpty():
self.front = (self.front - 1 + self.capacity) % self.capacity
self.q[self.front] = value
self.size += 1
return True
def insertLast(self, value: int) -> bool:
"""
Adds an item at the rear of Deque. Return true if the operation is successful.
"""
if self.isFull():
return False
idx = (self.front + self.size) % self.capacity
self.q[idx] = value
self.size += 1
return True
def deleteFront(self) -> bool:
"""
Deletes an item from the front of Deque. Return true if the operation is successful.
"""
if self.isEmpty():
return False
self.front = (self.front + 1) % self.capacity
self.size -= 1
return True
def deleteLast(self) -> bool:
"""
Deletes an item from the rear of Deque. Return true if the operation is successful.
"""
if self.isEmpty():
return False
self.size -= 1
return True
def getFront(self) -> int:
"""
Get the front item from the deque.
"""
if self.isEmpty():
return -1
return self.q[self.front]
def getRear(self) -> int:
"""
Get the last item from the deque.
"""
if self.isEmpty():
return -1
idx = (self.front + self.size - 1) % self.capacity
return self.q[idx]
def isEmpty(self) -> bool:
"""
Checks whether the circular deque is empty or not.
"""
return self.size == 0
def isFull(self) -> bool:
"""
Checks whether the circular deque is full or not.
"""
return self.size == self.capacity
# Your MyCircularDeque object will be instantiated and called as such:
# obj = MyCircularDeque(k)
# param_1 = obj.insertFront(value)
# param_2 = obj.insertLast(value)
# param_3 = obj.deleteFront()
# param_4 = obj.deleteLast()
# param_5 = obj.getFront()
# param_6 = obj.getRear()
# param_7 = obj.isEmpty()
# param_8 = obj.isFull()class MyCircularDeque {
private int[] q;
private int front;
private int size;
private int capacity;
/** Initialize your data structure here. Set the size of the deque to be k. */
public MyCircularDeque(int k) {
q = new int[k];
capacity = k;
}
/** Adds an item at the front of Deque. Return true if the operation is successful. */
public boolean insertFront(int value) {
if (isFull()) {
return false;
}
if (!isEmpty()) {
front = (front - 1 + capacity) % capacity;
}
q[front] = value;
++size;
return true;
}
/** Adds an item at the rear of Deque. Return true if the operation is successful. */
public boolean insertLast(int value) {
if (isFull()) {
return false;
}
int idx = (front + size) % capacity;
q[idx] = value;
++size;
return true;
}
/** Deletes an item from the front of Deque. Return true if the operation is successful. */
public boolean deleteFront() {
if (isEmpty()) {
return false;
}
front = (front + 1) % capacity;
--size;
return true;
}
/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
public boolean deleteLast() {
if (isEmpty()) {
return false;
}
--size;
return true;
}
/** Get the front item from the deque. */
public int getFront() {
if (isEmpty()) {
return -1;
}
return q[front];
}
/** Get the last item from the deque. */
public int getRear() {
if (isEmpty()) {
return -1;
}
int idx = (front + size - 1) % capacity;
return q[idx];
}
/** Checks whether the circular deque is empty or not. */
public boolean isEmpty() {
return size == 0;
}
/** Checks whether the circular deque is full or not. */
public boolean isFull() {
return size == capacity;
}
}
/**
* Your MyCircularDeque object will be instantiated and called as such:
* MyCircularDeque obj = new MyCircularDeque(k);
* boolean param_1 = obj.insertFront(value);
* boolean param_2 = obj.insertLast(value);
* boolean param_3 = obj.deleteFront();
* boolean param_4 = obj.deleteLast();
* int param_5 = obj.getFront();
* int param_6 = obj.getRear();
* boolean param_7 = obj.isEmpty();
* boolean param_8 = obj.isFull();
*/class MyCircularDeque {
public:
vector<int> q;
int front = 0;
int size = 0;
int capacity = 0;
MyCircularDeque(int k) {
q.assign(k, 0);
capacity = k;
}
bool insertFront(int value) {
if (isFull()) {
return false;
}
if (!isEmpty()) {
front = (front - 1 + capacity) % capacity;
}
q[front] = value;
++size;
return true;
}
bool insertLast(int value) {
if (isFull()) {
return false;
}
int idx = (front + size) % capacity;
q[idx] = value;
++size;
return true;
}
bool deleteFront() {
if (isEmpty()) {
return false;
}
front = (front + 1) % capacity;
--size;
return true;
}
bool deleteLast() {
if (isEmpty()) {
return false;
}
--size;
return true;
}
int getFront() {
return isEmpty() ? -1 : q[front];
}
int getRear() {
return isEmpty() ? -1 : q[(front + size - 1) % capacity];
}
bool isEmpty() {
return size == 0;
}
bool isFull() {
return size == capacity;
}
};
/**
* Your MyCircularDeque object will be instantiated and called as such:
* MyCircularDeque* obj = new MyCircularDeque(k);
* bool param_1 = obj->insertFront(value);
* bool param_2 = obj->insertLast(value);
* bool param_3 = obj->deleteFront();
* bool param_4 = obj->deleteLast();
* int param_5 = obj->getFront();
* int param_6 = obj->getRear();
* bool param_7 = obj->isEmpty();
* bool param_8 = obj->isFull();
*/type MyCircularDeque struct {
q []int
size int
front int
capacity int
}
func Constructor(k int) MyCircularDeque {
q := make([]int, k)
return MyCircularDeque{q, 0, 0, k}
}
func (this *MyCircularDeque) InsertFront(value int) bool {
if this.IsFull() {
return false
}
if !this.IsEmpty() {
this.front = (this.front - 1 + this.capacity) % this.capacity
}
this.q[this.front] = value
this.size++
return true
}
func (this *MyCircularDeque) InsertLast(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 *MyCircularDeque) DeleteFront() bool {
if this.IsEmpty() {
return false
}
this.front = (this.front + 1) % this.capacity
this.size -= 1
return true
}
func (this *MyCircularDeque) DeleteLast() bool {
if this.IsEmpty() {
return false
}
this.size -= 1
return true
}
func (this *MyCircularDeque) GetFront() int {
if this.IsEmpty() {
return -1
}
return this.q[this.front]
}
func (this *MyCircularDeque) GetRear() int {
if this.IsEmpty() {
return -1
}
return this.q[(this.front+this.size-1)%this.capacity]
}
func (this *MyCircularDeque) IsEmpty() bool {
return this.size == 0
}
func (this *MyCircularDeque) IsFull() bool {
return this.size == this.capacity
}
/**
* Your MyCircularDeque object will be instantiated and called as such:
* obj := Constructor(k);
* param_1 := obj.InsertFront(value);
* param_2 := obj.InsertLast(value);
* param_3 := obj.DeleteFront();
* param_4 := obj.DeleteLast();
* param_5 := obj.GetFront();
* param_6 := obj.GetRear();
* param_7 := obj.IsEmpty();
* param_8 := obj.IsFull();
*/class MyCircularDeque {
private vals: number[];
private length: number;
private size: number;
private start: number;
private end: number;
constructor(k: number) {
this.vals = new Array(k).fill(0);
this.start = 0;
this.end = 0;
this.length = 0;
this.size = k;
}
insertFront(value: number): boolean {
if (this.isFull()) {
return false;
}
if (this.start === 0) {
this.start = this.size - 1;
} else {
this.start--;
}
this.vals[this.start] = value;
this.length++;
return true;
}
insertLast(value: number): boolean {
if (this.isFull()) {
return false;
}
this.vals[this.end] = value;
this.length++;
if (this.end + 1 === this.size) {
this.end = 0;
} else {
this.end++;
}
return true;
}
deleteFront(): boolean {
if (this.isEmpty()) {
return false;
}
if (this.start + 1 === this.size) {
this.start = 0;
} else {
this.start++;
}
this.length--;
return true;
}
deleteLast(): boolean {
if (this.isEmpty()) {
return false;
}
if (this.end === 0) {
this.end = this.size - 1;
} else {
this.end--;
}
this.length--;
return true;
}
getFront(): number {
if (this.isEmpty()) {
return -1;
}
return this.vals[this.start];
}
getRear(): number {
if (this.isEmpty()) {
return -1;
}
if (this.end === 0) {
return this.vals[this.size - 1];
}
return this.vals[this.end - 1];
}
isEmpty(): boolean {
return this.length === 0;
}
isFull(): boolean {
return this.length === this.size;
}
}
/**
* 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()
*/