1>用C#写一段选择排序算法，要求用自己的编程风格。
答：private int min; public void xuanZhe(int[] list)//选择排序 { for (int i = 0; i < list.Length - 1; i++) { min = i; for (int j = i + 1; j < list.Length; j++) { if (list[j] < list[min]) min = j; } int t = list[min]; list[min] = list[i]; list[i] = t; } }
首先是二分查找法，时间复杂度O（2log2（n））：
static bool Find(int[] sortedArray, int number) { if (sortedArray.Length == 0) return false; int start = 0; int end = sortedArray.Length - 1; while (end >= start) { int middle = (start + end) / 2; if (sortedArray[middle] < number) start = middle + 1; else if (sortedArray[middle] > number) end = middle - 1; else return true; } return false; }然后是三分查找算法，时间复杂度O（3log3（n））： static bool Find(int[] sortedArray, int number) { if (sortedArray.Length == 0) return false; int start = 0; int end = sortedArray.Length - 1; while (end >= start) { int firstMiddle = (end - start) / 3 + start; int secondMiddle = end - (end - start) / 3; if (sortedArray[firstMiddle] > number) end = firstMiddle - 1; else if (sortedArray[secondMiddle] < number) start = secondMiddle + 1; else if (sortedArray[firstMiddle] != number && sortedArray[secondMiddle] != number) { end = secondMiddle - 1; start = firstMiddle + 1; } else return true; } return false; } 2>一列数的规则如下: 1、1、2、3、5、8、13、21、34...... 求第30位数是多少， 用递归算法实现。private static int Digui(int j){ if (j<=0)return 0;if (j == 1)return 1;return Digui(j-1) + Digui(j - 2);}1+2………………nprivate static int Digui1(int j){ if (j == 0)return 0;return Digui1(j - 1) + j;}写一个函数计算当参数为N的值:1-2+3-4+5-6+7……+N
答：public int returnSum(int n) { int sum = 0; for (int i = 1; i <= n; i++) { int k = i; if (i % 2 == 0) { k = -k; } sum = sum + k; } return sum; } public int returnSum1(int n) { int k = n; if (n == 0) { return 0; } if (n % 2 == 0) { k = -k; } return aaa(n - 1) + k; }
3>20个随机数列
Dictionary<string, int[]> dict = new Dictionary<string, int[]>(); ArrayList newArray; int[] intArray; Random rd; while (dict.Count < 20) { intArray = new int[5]; rd = new Random(); newArray = new ArrayList(); while (newArray.Count < 5) { int tempNumber = rd.Next(0, 10); if (!newArray.Contains(tempNumber)) newArray.Add(tempNumber); } string str=ArrayConvertToString(newArray); for (int i = 0; i < 5; i++) { intArray[i] = (int)newArray[i]; } if (!dict.ContainsKey(str)) { dict.Add(str, intArray); } } foreach (var l in dict) { Console.WriteLine(l.Key); } Console.WriteLine("@@" + dict.Keys.Max() + "@@" + dict.Keys.Min()); Console.ReadKey(); } static public string ArrayConvertToString(ArrayList al) { string strTemp=string.Empty; foreach (var aList in al) { strTemp += aList; } return strTemp; }4>
public abstract class A
{ public A() { Console.WriteLine('A'); } public virtual void Fun() { Console.WriteLine("A.Fun()"); } } public class B : A { public B() { Console.WriteLine('B'); } public new void Fun() { Console.WriteLine(" B.Fun()"); } public static void Main() { A a = new B(); a.Fun(); Console.Read(); } A B A.fun()public class A
{ public virtual void Fun1(int i) { Console.WriteLine(i); } public void Fun2(A a) { a.Fun1(1); Fun1(5); } } public class B : A { public override void Fun1(int i) { base.Fun1(i + 1); } public static void Main() { A a = new A(); B b = new B(); a.Fun2(b); b.Fun2(a); Console.Read(); } }2 5 1 6
6. 写出程序的输出结果class Class1 { private string str = "Class1.str"; private int i = 0;2 static void StringConvert(string str) { str = "string being converted."; } static void StringConvert(Class1 c) { c.str = "string being converted."; } static void Add(int i) { i++; } static void AddWithRef(ref int i) { i++; } static void Main() { int i1 = 10; int i2 = 20; string str = "str"; Class1 c = new Class1(); Add(i1); AddWithRef(ref i2);21 Add(c.i); StringConvert(str); StringConvert(c); Console.WriteLine(i1); Console.WriteLine(i2); Console.WriteLine(c.i); Console.WriteLine(str); Console.WriteLine(c.str); } }答：10，21，0，str，string being converted.10. 程序设计: 猫大叫一声，所有的老鼠都开始逃跑，主人被惊醒。(C#语言)要求： 1.要有联动性，老鼠和主人的行为是被动的。2.考虑可扩展性，猫的叫声可能引起其他联动效应。 public interface Observer { void Response(); //观察者的响应，如是老鼠见到猫的反映 } public interface Subject { void AimAt(Observer obs); //针对哪些观察者，这里指猫的要扑捉的对象---老鼠 } public class Mouse : Observer { private string name; public Mouse(string name, Subject subj) { this.name = name; subj.AimAt(this); } public void Response() { Console.WriteLine(name + " attempt to escape!"); } } public class Master : Observer { public Master(Subject subj) { subj.AimAt(this); } public void Response() { Console.WriteLine("Host waken!"); } } public class Cat : Subject { private ArrayList observers; public Cat() { this.observers = new ArrayList(); } public void AimAt(Observer obs) { this.observers.Add(obs); } public void Cry() { Console.WriteLine("Cat cryed!"); foreach (Observer obs in this.observers) { obs.Response(); } } } class MainClass { 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(); } }//---------------------------------------------------------------------------------------------设计方法二: 使用event -- delegate设计.. 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"); } } class Class1 { 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(); } }