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[Java教程]225. Implement Stack using Queues


代码如下:

class MyStack {  // Push element x onto stack.  Queue<Integer> queue=new ArrayDeque<>();    public void push(int x) {     Queue<Integer> p=new ArrayDeque<>();                                   int c=queue.size();    while(c!=0)    {      p.offer(queue.peek());      queue.remove();      c--;    }    queue.offer(x);    int d=p.size();     while(d!=0)    {      queue.offer(p.peek());      p.remove();      d--;    }      }  // Removes the element on top of the stack.  public void pop() {     queue.remove();  }  // Get the top element.  public int top() {    return queue.peek();  }  // Return whether the stack is empty.  public boolean empty() {    if(queue.size()==0)    return true;    return false;  }}