java-leetcode题解之第622题设计循环队列.zip

public class MyCircularQueue { private int[] arr; private int capacity; /** * front 指向当前队列中最早入队的元素 */ private int front; /** * rear 指向下一个添加到队尾的元素 */ private int rear; /** * Initialize your data structure here. Set the size of the queue to be k. */ public MyCircularQueue(int k) { // 始终保持 1 个位置不存有效元素，是为了避免判断队列为空和队列为满的条件冲突 capacity = k + 1; arr = new int[capacity]; front = 0; rear = 0; } /** * Insert an element into the circular queue. Return true if the operation is successful. */ public boolean enQueue(int value) { // 队尾为满不可以入队 if (isFull()) { return false; } arr[rear] = value; rear = (rear + 1) % capacity; return true; } /** * Delete an element from the circular queue. Return true if the operation is successful. */ public boolean deQueue() { // 队尾为空不可以出队 if (isEmpty()) { return false; } front = (front + 1) % capacity; return true; } /** * Get the front item from the queue. */ public int Front() { // 队列非空才可以取出队头 if (isEmpty()) { return -1; } return arr[front]; } /** * Get the last item from the queue. */ public int Rear() { // 队列非空才可以取出队尾 if (isEmpty()) { return -1; } // 有数组下标的计算一定要考虑是否越界 return arr[(rear - 1 + capacity) % capacity]; } /** * Checks whether the circular queue is empty or not. */ public boolean isEmpty() { return front == rear; } /** * Checks whether the circular queue is full or not. */ public boolean isFull() { // 有数组下标的计算一定要考虑是否越界 return (rear + 1) % capacity == front; } }