3. 无重复字符的最长子串

给定一个字符串 s ，请你找出其中不含有重复字符的 最长子串 的长度。

public class Solution {
    
    
    public int LengthOfLongestSubstring(string s) {
    
    
               string maxString = "";//最长的字符串
            string currentString = "";//用于记录现在的字符串

            for (int i = 0; i < s.Length; i++)
            {
    
    
                currentString = currentString + s[i];
                for (int j = i; j < s.Length - 1; j++)
                {
    
    
                    int myindex = currentString.IndexOf(s[j + 1]);

                    if (myindex == -1)//不存在
                    {
    
    
                        currentString = currentString + s[j + 1];
                    }
                    else
                    {
    
    
                        break;
                    }
                }
                if (currentString.Length > maxString.Length)
                {
    
    
                    maxString = currentString;
                    currentString = "";
                }
                currentString = "";
            }

            Console.WriteLine(maxString);
            return maxString.Length;
    }
}