622. Design Circular Queue - Medium

前往題目

想法

• 自創node組成linkedlist

思路

enQueue: 檢查是否已滿，未滿時可以加入新的node，如果是唯一一個，頭尾都是相同的node **deQueue**: 如果為空就false，否則彈出head`，並且大小減一

Code

網友解答

class MyCircularQueue {


    int size;
    int maxSize;
    Node head;
    Node tail;

    public MyCircularQueue(int k) {
        size = 0;
        maxSize = k;
        head = null;
        tail = null;
    }
    
    public boolean enQueue(int value) {
        // Full already
        if (isFull()) return false;
        // Declare the new node
        Node newNode = new Node(value);
        // Add to the empty queue
        if (isEmpty()) {
            head = newNode;
            tail = newNode;
        } else {
            tail.next = newNode;
            tail = tail.next;
        }
        ++size;
        return true;
    }
    
    public boolean deQueue() {
        // Empty already
        if (isEmpty()) return false;
        head = head.next;
        --size;
        return true;
    }
    
    public int Front() {
        return isEmpty() ? -1 : head.val;
    }
    
    public int Rear() {
        return isEmpty() ? -1 : tail.val;
    }
    
    public boolean isEmpty() {
        return size == 0;
    }
    
    public boolean isFull() {
        return size == maxSize;
    }

    private class Node {
        Node next;
        int val;

        public Node(int val) {
            this.next = null;
            this.val = val;
        }
    }
}