算法练习(15) - 两个队列实现栈

import java.util.LinkedList;

class MyStack {

    LinkedList<Integer> data ;
    LinkedList<Integer> revers ;
    LinkedList<Integer> temp ;

    /** Initialize your data structure here. */
    public MyStack() {
         data = new LinkedList<>();
        revers = new LinkedList<>();
    }
    
    /** Push element x onto stack. */
    public void push(int x) {
        if (data.isEmpty()){
            data.offer(x);
        }else{
            if(!data.isEmpty()){
                revers.offer(x);
            }
            while(!data.isEmpty()){
                revers.offer(data.pop());
            }
            temp = revers;
            revers = data;
            data = temp;
        }
        System.out.println(data);
    }
    
    /** Removes the element on top of the stack and returns that element. */
    public int pop() {
        return data.pop();
    }
    
    /** Get the top element. */
    public int top() {
        return  data.getFirst();
    }
    
    /** Returns whether the stack is empty. */
    public boolean empty() {
        return   data.isEmpty();
    }
}