循环队列实现 622.Design Circular Queue

import java.util.*;

class MyCircularQueue {

    public int[] data; 
    private int p_start;
    private int p_tail;
    private int k;
    private int len;

    /** Initialize your data structure here. Set the size of the queue to be k. */
    public MyCircularQueue(int k) {
        data = new int [k];
        p_start = 0;
        p_tail = -1;
        this.k = k;
        len = 0;
    }
    
    /** Insert an element into the circular queue. Return true if the operation is successful. */
    public boolean enQueue(int value) {
        if(isFull())
            return false;
        /*if(p_tail == 0 && p_start == 0) {
        	data[p_tail] = value;
        	len++;
        	return true;
        }*/
        //solving wrap-up case
        if(++p_tail > k - 1)
           p_tail = 0;
        data[p_tail] = value;
        len++;
        return true;
    }
    
    /** Delete an element from the circular queue. Return true if the operation is successful. */
    public boolean deQueue() {
        if(isEmpty()){
            return false;
        }
        //solving wrap-up case
        if(++p_start > k - 1)
            p_start = 0;
        len--;
        return true;
    }
    
    /** Get the front item from the queue. */
    public int Front() {
    	if(isEmpty())
    		return -1;
        return data[p_start];
    }
    
    /** Get the last item from the queue. */
    public int Rear() {
    	if(isEmpty())
    		return -1;
        return data[p_tail];
    }
    
    /** Checks whether the circular queue is empty or not. */
    public boolean isEmpty() {
        if(len ==0)
        	return true;
        else 
        	return false;
    }
    
    /** Checks whether the circular queue is full or not. */
    public boolean isFull() {
    	if(len == k)
    		return true;
    	else
    		return false;
 
    }
    

}

/**
 * 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();
 */

写的时候把头尾都初始化成0，结果就写的很费劲，后来想到可以把tail初始化成-1，问题就解决了。