LeetCode之Implement Stack using Queues

写在前面：第一次快速accepted，而且53 ms, faster than 98.61% of Java online submissions for Implement Stack using Queues.但是使用的是数组，貌似不是严格符合题目要求。

1. 使用Array

class MyStack {
    private int top;
    private int[] stack;
    /** Initialize your data structure here. */
    public MyStack() {
        this.top = -1;
        this.stack = new int[500];
        
    }
    
    /** Push element x onto stack. */
    public void push(int x) {
        this.stack[++top] = x;
    }
    
    /** Removes the element on top of the stack and returns that element. */
    public int pop() {
        int pop = stack[top--];
        return pop;
    }
    
    /** Get the top element. */
    public int top() {
        return stack[top];
    }
    
    /** Returns whether the stack is empty. */
    public boolean empty() {
        return top==-1?true:false;
    }
}

/**
 * Your MyStack object will be instantiated and called as such:
 * MyStack obj = new MyStack();
 * obj.push(x);
 * int param_2 = obj.pop();
 * int param_3 = obj.top();
 * boolean param_4 = obj.empty();
 */

2. 使用LinkList

class MyStack {
    Queue queue;
    /** Initialize your data structure here. */
    public MyStack() {
        this.queue = new LinkedList<>();//注意链表是先进先出
    }
    
    /** Push element x onto stack. */
    public void push(int x) {
        queue.add(x);
        for(int i =0;i