C#常见算法面试题小结

  //冒泡排序
  public class bubblesorter
  {
    public void sort(int[] list)
    {
      int i, j, temp;
      bool done = false;
      j = 1;
      while ((j < list.Length) && (!done))
      {
        done = true;
        for (i = 0; i < list.Length - j; i++)
        {
          if (list[i] > list[i + 1])
          {
            done = false;
            temp = list[i];
            list[i] = list[i + 1];
            list[i + 1] = temp;
          }
        }
          j++;
      }
    }
  }
  //选择排序
  public class selectionsorter
  {
    private int min;
    public void sort(int[] list)
    {
      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;
      }
    }
  }
  //插入排序
  public class insertionsorter
  {
    public void sort(int[] list)
    {
      for (int i = 1; i < list.Length; i++)
      {
        int t = list[i];
        int j = i;
        while ((j > 0) && (list[j - 1] > t))
        {
          list[j] = list[j - 1];
          --j;
        }
        list[j] = t;
      }
    }
  }

public class MainClass
{
  public static void Main()
  {
    Console.WriteLine(Foo(30));
  }
  public static int Foo(int i)
  {
    if (i <= 0)
      return 0;
    else if (i > 0 && i <= 2)
      return 1;
    else return Foo(i - 1) + Foo(i - 2);
  }
}

  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(); 
    } 
  } 

static string Reverse() 
{ 
 string s = "I am a good man"; 
 string[] arr = s.Split(' '); 
 string res = ""; 
 for (int i = arr.Length - 1; i >= 0; i--) 
 { 
   res += arr[i]; 
   if (i > 0) 
  res += " "; 
 } 
 return res; 
}

static void Main(string[] args)
{
  char[] name={'A','B','C','D','E'};
  int[] value = new int[5];
  for (value[0]=0;value[0]<2;value [0]++)
 for (value[1]=0; value[1] < 2; value[1]++)
   for (value[2]=0; value[2] < 2; value[2]++)
 for (value[3]=0; value[3] < 2; value[3]++)
   for (value[4]=0; value[4] < 2; value[4]++)
   {
  if ((value[1] >= value[0]) && (value[1] + value[2] == 1) && (value[2] == value[3]) && (value[3] + value[4]==1) && (value[4]==0 || value[4]==1 && value[0]==1 && value[3]==1))
  {
    for (int i = 0; i < 5; i++)
    {
  if (value[i]==1)
  {
    Console.WriteLine("{0}参加", name[i]);
  }
  else
  {
    Console.WriteLine("{0}不参加", name[i]);
  }
    }
  }
   }
}

static int StringTolnt(string s)
{
  int sum = 0;
  for (int i = 0; i < s.Length; i++)
 sum = sum * 10 + (s[i] - '0');
  return sum;
}