面试题 7: 两个栈实现一个队列

一. 题目

用两个栈实现一个队列,并完成在队列尾部插入结点和在队列头部删除结点的功能.

代码请到我的代码库中下载 Point2Offer

二. 代码

package week_4;

import java.util.Stack;

/**难度系数:**
 * 剑指offer: 两个栈实现一个队列
 * 方法: 队尾插入,队头删除
 * 测试用例:功能测试(空的队列添加删除,非空的添加删除,连续删除置为空)
 * @author dingding
 * Date:2017-7-6 8:30
 * Declaration: All Rights Reserved!
 */
public class No7 {

    public static void main(String[] args){
        test1();
    }
    //定义一个队列
    public static class CQueue<T>{
        private  Stack<T> stack1= new Stack<>();
        private  Stack<T> stack2= new Stack<>();

        public CQueue(){

        }
        //solution,队头添加
        private void appendTail(T number){
            stack1.add(number);
        }

        //队尾删除
        private  T deleteHead(){
            //栈2为空,把栈1值取出放入2
            if (stack2.isEmpty()) {
                while (!stack1.isEmpty()){
                    stack2.add(stack1.pop());
                }
            }
            if (stack2.isEmpty()) {
                throw new RuntimeException("No more element.");
            }

            return stack2.pop();
        }
    }



    /*=======================测试用例==================*/
    private static void test1(){
        CQueue<Integer> cQueue = new CQueue<>();
        for (int i=0;i<5;i++){
            cQueue.appendTail(i);
        }
        Integer head = cQueue.deleteHead();
        System.out.println("删除队头为: "+ head);
        cQueue.appendTail(5);
        System.out.print(" "+cQueue.deleteHead());
        System.out.print(" "+cQueue.deleteHead());
        System.out.print(" "+cQueue.deleteHead());
        System.out.print(" "+cQueue.deleteHead());
        System.out.print(" "+cQueue.deleteHead());
    }
}

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有不妥当之处,麻烦告知:D