题目地址 (opens new window)

• 😣 第一次练习 2020年3月22日 双端循环队列，最开始没啥思路，但是看了人家的实现，发现这个病不难，心里大概有数，后面可以再来实现以下 🐂🍻
• 💩 第二次练习

利用数组实现

//leetcode submit region begin(Prohibit modification and deletion)
class MyCircularDeque {
    int[] myqueue;
    // 对头指针
    int front;
    // 队尾指针
    int rear;
    // 队列当前的大小
    int size;
    // 队列的容量
    int capacity;

    /** Initialize your data structure here. Set the size of the deque to be k. */
    public MyCircularDeque(int k) {
        this.myqueue = new int[k];
        this.front = 0;
        this.rear = 0;
        this.size = 0;
        this.capacity = k;
    }
    
    /** Adds an item at the front of Deque. Return true if the operation is successful. */
    public boolean insertFront(int value) {
        // 如果队列满，则插入失败
        if (rear == front && size == capacity) {
            return false;
        } else {
            front = (front + capacity - 1) % capacity;
            myqueue[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) {
        // 如果队列满，插入失败
        if (rear == front && size == capacity) {
            return false;
        } else {
            myqueue[rear] = value;
            rear = (rear + 1 + capacity) % capacity;
            size ++;
            return true;
        }
    }
    
    /** Deletes an item from the front of Deque. Return true if the operation is successful. */
    public boolean deleteFront() {
        if (rear == front && size == 0)
            return false;
        else {
            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 (rear == front && size == 0)
            return false;
        else {
            rear = (rear - 1 + capacity) % capacity;
            size --;
            return true;
        }
    }

    /**
     * Get the front item from the deque.
     */
    public int getFront() {
        if (rear == front && size == 0)
            return -1;
        else {
            return myqueue[front];
        }
    }
    
    /** Get the last item from the deque. */
    public int getRear() {
        if (rear == front && size == 0)
            return -1;
        else {
            return myqueue[(rear - 1 + capacity) % capacity];
        }
    }
    
    /** Checks whether the circular deque is empty or not. */
    public boolean isEmpty() {
        return (rear == front) && size == 0;
    }
    
    /** Checks whether the circular deque is full or not. */
    public boolean isFull() {
        return rear == front && 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();
 */
//leetcode submit region end(Prohibit modification and deletion)

易错点

• 易错项 1