找出字符串的最长不重复子串，输出最大的子字符串

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplication4
{
    class Program
{
        static void Main(string[] args)
{
            string s = "abcababcdefgfg";
            char[] list = s.ToCharArray();
            FindMaxSubDifferenceString ss = new FindMaxSubDifferenceString();
ss.FindMaxSubDifferenceStringS(list, s.Length);
            string s1 = "aaaaaa";
            char[] list1 = s1.ToCharArray();
ss.FindMaxSubDifferenceStringS(list1, s1.Length);
            string s2 = "ababab";
            char[] list2 = s2.ToCharArray();
ss.FindMaxSubDifferenceStringS(list2, s2.Length);
            string s3 = "abcababcdefgfgabcababcdefgfg";
            char[] list3 = s3.ToCharArray();

ss.FindMaxSubDifferenceStringS(list3, s3.Length);
}

}
　
    public class FindMaxSubDifferenceString
{
        public bool IsDup(char[] list, int len, char targetChar, int begin, int end, out int targetIndex)
{
targetIndex = -1;
            // Note: first, we need to check all parameters are valid, such as list is null, len >0, or begin <end, begin>0, end<len, etc
            for(int i=begin;i<=end; i++)
{
                if(list[i]==targetChar)
{
targetIndex = i;
                    return true;
}
}
　
            return false;
}
        public void FindMaxSubDifferenceStringS(char[] list, int len)
{
            if (list == null) return;
            if (len <= 0) return;
            int maxSubStringLen = 0;
            int maxSubStringBeginIndex = 0;
            int currentMaxSubStringBeginIndex = 0;
            int currentMaxSubLen = 0;
            for (int i = 1; i < len; i++)
{
                int dupIndex = -1;
                if (IsDup(list, len, list[i], currentMaxSubStringBeginIndex, i - 1, out dupIndex))
{
currentMaxSubLen = i - currentMaxSubStringBeginIndex;
                    if (currentMaxSubLen > maxSubStringLen)
{
maxSubStringLen = currentMaxSubLen;
maxSubStringBeginIndex = currentMaxSubStringBeginIndex;
}
                    else
{
}
currentMaxSubStringBeginIndex = dupIndex + 1;
}
                else //not dup
{
}
}
　
            if (maxSubStringLen == 0)
{
maxSubStringLen = len;
}
            Console.Write("Input string: ");
            for (int i = 0; i < len; i++)
{
                Console.Write(list[i]);
}
            Console.WriteLine("");
            Console.Write("After Input: ");
            for (int i = maxSubStringBeginIndex; i < maxSubStringBeginIndex + maxSubStringLen; i++)
{
                Console.Write(list[i]);
}
            Console.WriteLine("");
}

}
}