Implement Stack using Queues/Implement Queue using Stacks

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题目地址：https://leetcode.com/submissions/detail/88638615/，https://leetcode.com/submissions/detail/88638372/

无论是用栈实现队列还是用队列实现栈，在Java中提供给了我们LinkedList这样一个容器，它的操作足以满足我们模拟队列与栈的操作。

队列模拟栈

public class ImplementStackUsingQueues {LinkedList<Integer> queue = new LinkedList<>();// Push element x onto stack.public void push(int x) {queue.push(x);}// Removes the element on top of the stack.public void pop() {queue.pop();}// Get the top element.public int top() {return queue.peek();}// Return whether the stack is empty.public boolean empty() {return queue.size() == 0 ? true : false;}
}

栈模拟队列：

public class ImplementQueueUsingStacks {LinkedList<Integer> stack = new LinkedList<>();// Push element x to the back of queue.public void push(int x) {stack.add(x);}// Removes the element from in front of queue.public void pop() {stack.pop();}// Get the front element.public int peek() {return stack.peek();}// Return whether the queue is empty.public boolean empty() {return stack.size() == 0 ? true : false;}@Overridepublic String toString() {return stack.toString();}public static void main(String[] args) {ImplementQueueUsingStacks queue = new ImplementQueueUsingStacks();queue.push(1);queue.push(2);queue.push(3);queue.push(4);System.out.println(queue);System.out.println(queue.peek());queue.pop();System.out.println(queue.peek());System.out.println(queue.empty());queue.pop();System.out.println(queue);}
}