3. Longest Substring Without Repeating Characters

leetcode3.cs

public class Solution
{
    public int LengthOfLongestSubstring(string s)
    {
        int subLength = 0;
        int r = 0;
        int repetitionIndex;
        int start = 0;
        for (int i = 0; i < s.Length; i++)
        {
            repetitionIndex = s.Substring(start, i - start).LastIndexOf(s[i]);
            if (repetitionIndex > -1)
            {
                repetitionIndex += start;
            }
            if (subLength >= i - repetitionIndex)
            {
                subLength = i - repetitionIndex;
                start = repetitionIndex + 1;
            }
            else
            {
                subLength += 1;
                if (r < subLength)
                {
                    r = subLength;
                }
            }
        }
        return r;
    }
}