C#常见算法题目(面试准备)
1.写出冒泡，选择，插入排序算法。
//冒泡排序
public class bubblesorter
{
public void sort(int[] list)
{
int length = list.Length;
for (int i = 0; i < length; i++)
{
for (int j = length - 1; j > i; j--)
{
if (list[j - 1] > list[j])
{
int temp;
temp = list[j];
list[j] = list[j - 1];
list[j - 1] = temp;
}
}
}
}
}
//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;
}
}
}
2.有一列数1，1，2，3，5，........求第30个数.
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);
}
}
3. 程序设计: 猫大叫一声，所有的老鼠都开始逃跑，主人被惊醒。
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();
}
}
4.有一个字符串 "I am a good man",设计一个函数,返回 "man good a am I"。
5.Ａ、Ｂ、Ｃ、Ｄ、Ｅ五名学生有可能参加计算机竞赛，根据下列条件判断哪些
人参加了竞赛：
（１）Ａ参加时，Ｂ也参加；
（２）Ｂ和Ｃ只有一个人参加；
（３）Ｃ和Ｄ或者都参加，或者都不参加；
（４）Ｄ和Ｅ中至少有一个人参加；
（５）如果Ｅ参加，那么Ａ和Ｄ也都参加。
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]);
}
}
}
}
}
6.题目：
a user entered an integer value into a text box. Without using a buit-in library, convert the numeric string to its integer representation.
static int StringTolnt(string s)
{
int sum = 0;
for (int i = 0; i < s.Length; i++)
sum = sum * 10 + (s[i] - '0');
return sum;
}
