C#经典机试题(更新中)

一.程序设计：猫大叫一声，所有的老鼠都开始逃跑，主人被惊醒。

要求：一要有联动性，老鼠和主人的行为是被动的。二考虑可扩展性，猫的叫声可能引起其他联动效应。

答案：

1.使用inerface设计：

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

 class Program
    {
        static void Main(string[] args)
        {
            Cat cat = new Cat();
            Mouse mouse1 = new Mouse("mouse1", cat);
            Mouse mouse2 = new Mouse("mouse2", cat);
            Master master = new Master(cat);
            cat.Cry();
        }
    }
    public interface Observer
    {
        void Response();    //观察者的响应，如果是老鼠见到猫的反应
    }
    public interface Subject
    {
        void AmiAt(Observer obs);   //针对哪些观察者，这里指猫要捕捉的对象--老鼠
    }
    public class Mouse : Observer
    {
        private string name;
        public Mouse(string name,Subject subj)
        {
            this.name = name;
            subj.AmiAt(this);
        }
        public void Response()
        {
            Console.WriteLine(name + " run!");
        }
    }
    public class Master : Observer
    {
        public Master(Subject subj)
        {
            subj.AmiAt(this);
        }
        public void Response()
        {
            Console.WriteLine("Host waken!");
        }
    }
    public class Cat : Subject
    {
        private ArrayList Observers;
        public Cat()
        {
            this.Observers = new ArrayList();
        }
        public void AmiAt(Observer obs)
        {
            this.Observers.Add(obs);
        }
        public void Cry()
        {
            Console.WriteLine("Cat cryed!");
            foreach (Observer obs in this.Observers)
            {
                obs.Response();
            }
        }
    }

2.使用event-delegate设计：

using System;
using System.Collections.Generic;
using System.Text;

class Program
    {
        static void Main(string[] args)
        {
            Cat cat = new Cat();
            Mouse mouse1 = new Mouse("mouse1", cat);
            Mouse mouse2 = new Mouse("mouse2", cat);
            Master master = new Master(cat);
            cat.Cry();
        }
    }
    public delegate void SubEventHandler();
    public abstract class Subject
    {
        public event SubEventHandler SubEvent;
        protected void FireAway()
        {
            if (this.SubEvent != null)
            {
                this.SubEvent();
            }
        }
    }
    public class Cat : Subject
    {
        public void Cry()
        {
            Console.WriteLine("cat cryed.");
            this.FireAway();
        }
    }
    public abstract class Observer
    {
        public Observer(Subject sub)
        {
            sub.SubEvent+=new SubEventHandler(Response);
        }
        public abstract void Response();
    }
    public class Mouse : Observer
    {
        private string name;
        public Mouse(string name, Subject sub)
            : base(sub)
        {
            this.name = name;
        }
        public override void Response()
        {
            Console.WriteLine(name + " attempt to escape!");
        }
    }
    public class Master : Observer
    {
        public Master(Subject sub)
            : base(sub)
        { }
        public override void Response()
        {
            Console.WriteLine("host waken");
        }
    }