Design Circular Deque
作者：互联网
Design your implementation of the circular double-ended queue (deque).
Your implementation should support following operations:
MyCircularDeque(k): Constructor, set the size of the deque to be k.insertFront(): Adds an item at the front of Deque. Return true if the operation is successful.insertLast(): Adds an item at the rear of Deque. Return true if the operation is successful.deleteFront(): Deletes an item from the front of Deque. Return true if the operation is successful.deleteLast(): Deletes an item from the rear of Deque. Return true if the operation is successful.getFront(): Gets the front item from the Deque. If the deque is empty, return -1.getRear(): Gets the last item from Deque. If the deque is empty, return -1.isEmpty(): Checks whether Deque is empty or not.isFull(): Checks whether Deque is full or not.
Example:
MyCircularDeque circularDeque = new MycircularDeque(3); // set the size to be 3 circularDeque.insertLast(1); // return true circularDeque.insertLast(2); // return true circularDeque.insertFront(3); // return true circularDeque.insertFront(4); // return false, the queue is full circularDeque.getRear(); // return 2 circularDeque.isFull(); // return true circularDeque.deleteLast(); // return true circularDeque.insertFront(4); // return true circularDeque.getFront(); // return 4
1 class MyCircularDeque {
2 int[] a;
3 int front, rear, cap, size;
4
5 public MyCircularDeque(int k) {
6 a = new int[k];
7 cap = k;
8 }
9
10 /** Adds an item at the front of Deque. Return true if the operation is successful. */
11 public boolean insertFront(int value) {
12 if(isFull()) return false;
13 // because we set the initial value of front to be 0
14 if (size != 0) {
15 front = (front - 1 + cap) % cap;
16 }
17 a[front] = value;
18 size++;
19 return true;
20 }
21
22 /** Adds an item at the rear of Deque. Return true if the operation is successful. */
23 public boolean insertLast(int value) {
24 if(isFull()) return false;
25 // because we set the initial value of rear to be 0
26 if (size != 0) {
27 rear = (rear + 1) % cap;
28 }
29 a[rear] = value;
30 size++;
31 return true;
32 }
33
34 /** Deletes an item from the front of Deque. Return true if the operation is successful. */
35 public boolean deleteFront() {
36 if(isEmpty()) return false;
37 size--;
38 if (size != 0) {
39 front = (front + 1) % cap;
40 }
41 return true;
42 }
43
44 /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
45 public boolean deleteLast() {
46 if(isEmpty()) return false;
47 size--;
48 if (size != 0) {
49 rear = (rear - 1 + cap) % cap;
50 }
51 return true;
52 }
53
54 /** Get the front item from the deque. */
55 public int getFront() {
56 return isEmpty() ? -1 : a[front];
57 }
58
59 /** Get the last item from the deque. */
60 public int getRear() {
61 return isEmpty() ? -1 : a[rear];
62 }
63
64 /** Checks whether the circular deque is empty or not. */
65 public boolean isEmpty() {
66 return size == 0;
67 }
68
69 /** Checks whether the circular deque is full or not. */
70 public boolean isFull() {
71 return size == cap;
72 }
73 }
标签：Deque,return,Design,front,size,true,rear,Circular 来源： https://www.cnblogs.com/beiyeqingteng/p/11333975.html