为什么在用到递归的时候总是没有头绪 - 黑马程序员技术交流社区

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("请输入任意字符！");
string str;
LuRuZiFu:
str = Console.ReadLine();
if (str == string.Empty)
{
Console.WriteLine("不能输入空字符串，请重新输入！");
goto LuRuZiFu;
}
for (int i = 0; i < str.Length; i++)
{
char temp = str[i];
int suoyin = str.IndexOf(temp);
if (suoyin != i && suoyin != -1)
{
Console.WriteLine("字符串有重复的字符，请重新输入！");
goto LuRuZiFu;
}
}
Console.Write("可能出现的字符！");
PaiLieZuHe(str.ToCharArray(), 0, str.Length);
Console.ReadKey();
}
static void JiaoHuan(ref char a, ref char b)
{
char temp = a;
a = b;
b = temp;
}
static void PaiLieZuHe(char[] jiaohuanwenben, int kaishi, int jieshu)
{
//交换到最后一位
if (kaishi == jieshu - 1)
{
Console.Write(new string(jiaohuanwenben) + " ");
}
else
{
for (int i = kaishi; i < jieshu; i++)
{
JiaoHuan(ref jiaohuanwenben[i], ref jiaohuanwenben[kaishi]);
PaiLieZuHe(jiaohuanwenben, kaishi + 1, jieshu);
JiaoHuan(ref jiaohuanwenben[i], ref jiaohuanwenben[kaishi]);
}
}
}
}
}

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace 一个数字的所有进制显示用递归表示出来
{
class Program
{
static void Main(string[] args)
{
List<List<char>> suoyoujinzhi = new List<List<char>>();
Console.WriteLine("请输入数字");
int tempint = Convert.ToInt32(Console.ReadLine());
SuoYouJinZhi(tempint, 2, 16, suoyoujinzhi);
foreach (var item in suoyoujinzhi)
{
string str = new string(item.ToArray());
Console.WriteLine(str);
}
Console.ReadKey();
}
static char PiPeiZiFu(int i)
{
switch (i)
{
case 10:
return 'A';
case 11:
return 'B';
case 12:
return 'C';
case 13:
return 'D';
case 14:
return 'E';
case 15:
return 'F';
default:
return Convert.ToChar(i.ToString());
}
}
static void SuoYouJinZhi(int shuzi, int kaishi, int jieshu, List<List<char>> suoyoujinzhi)
{
if (kaishi == jieshu + 1)
{
return;
}
else
{
//保存输入数字的值
int tempint = shuzi;
//创建一个字符串用来保存所得到的N进制结果
List<char> temp = new List<char>();
while (shuzi >= kaishi)
{
//把余数加入到字符串开头
temp.Insert(0, PiPeiZiFu(shuzi % kaishi));
//更新原数字。
shuzi /= kaishi;
}
//如果剩余的数字不是0那就把它加到开头
if (shuzi != 0)
{
temp.Insert(0, PiPeiZiFu(shuzi));
}
//在开头加上是多少进制。
temp.InsertRange(0, string.Format("{0}进制结果：", kaishi).ToCharArray());
//把第N进制的结果保存到所有进制里
suoyoujinzhi.Add(temp);
// 进行下一个进制的计算
SuoYouJinZhi(tempint, ++kaishi, jieshu, suoyoujinzhi);
}
}
}
}

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace 求数组中最大数
{
class Program
{
static void Main(string[] args)
{
int[] shuzu = new int[] { 10, 2, 5, 611, 111, 45, 123 };
int weizhi = ZuiDaShuWeiZhi(shuzu, 0, 0);
Console.WriteLine("最大数为{0}", shuzu[weizhi]);
Console.ReadKey();
}
static int ZuiDaShuWeiZhi(int[] a, int weizhi, int i)
{
if (i == a.Length)
{
return weizhi;
}
if (a[i] > a[weizhi])
{
return ZuiDaShuWeiZhi(a, i, ++i);
}
return ZuiDaShuWeiZhi(a, weizhi, ++i);
}
}
}

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace 递归
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("1,2,3....n");
Console.WriteLine("n为？");
string str = Console.ReadLine();
Console.WriteLine(DiGui(Convert.ToInt32(str) - 1));
Console.ReadKey();
}
static int DiGui(int n)
{
if (n == 0)
{
return 1;
}
if (n == 1)
{
return 2;
}
return DiGui(n - 2) + DiGui(n - 1);
}
}
}

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace 求n个整数的乘积
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine(ChengJi(6));
Console.ReadKey();
}
static int ChengJi(int i)
{
if (i == 1)
{
return 1;
}
return i * ChengJi(--i);
}
}
}

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