两个队列实现栈--Java实现

ゝ一纸荒年。 2023-01-13 06:22 136阅读 0赞

import java.util.LinkedList;
    import java.util.Queue;
    
    /** * @author mazhen * @className QueueToStack * @Description 两个队列实现栈 * @date 2021/3/29 10:26 */
    public class QueueToStack { 
    
        Queue<Integer> queue1 = new LinkedList<>();
        Queue<Integer> queue2 = new LinkedList<>();
    
        //入栈
        public void push(Integer x) { 
            queue1.add(x);
        }
    
        //栈大小
        public int stackSize() { 
            return queue1.size() + queue2.size();
        }
    
        //把一个队列的n-1个元素转出放入到另一个队列
        private void transferToAnother () { 
            if (!queue1.isEmpty()) { 
                while (queue1.size()>1) { 
                    queue2.add(queue1.poll());
                }
            } else if (!queue2.isEmpty()) { 
                while (queue2.size()>1) { 
                    queue1.add(queue2.poll());
                }
            }
        }
    
        //出栈
        public Integer poll() { 
            if (stackSize() <= 0) { 
                System.out.println("栈已空");
                return -1;
            } else { 
                if (queue1.size()>0) { 
                    transferToAnother();
                    return queue1.poll();
                } else if (queue2.size()>0) { 
                    transferToAnother();
                    return queue2.poll();
                }
            }
            return -1;
        }
    
        public static void main(String[] args) { 
            QueueToStack queueToStack = new QueueToStack();
            queueToStack.push(1);
            queueToStack.push(2);
            queueToStack.push(3);
            queueToStack.push(4);
            System.out.println(queueToStack.poll());
            System.out.println(queueToStack.poll());
            System.out.println(queueToStack.poll());
            System.out.println(queueToStack.poll());
        }
    
    }

参考：[https://blog.csdn.net/u011328417/article/details/79436120][https_blog.csdn.net_u011328417_article_details_79436120]

[https_blog.csdn.net_u011328417_article_details_79436120]: https://blog.csdn.net/u011328417/article/details/79436120