Longest Substring Without Repeating Characters

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        indexMap = {}
        l = 0
        border1 = 0
        border2 = 0
        index = 0
        result = 0
        for char in s:
            if indexMap.get(char) is None:
                l += 1
                result = max(l , result)
                indexMap[char] = index
                print(indexMap[char])
                border2 = index
            else :
                if indexMap.get(char) < border1:
                    l += 1 
                    result = max(l , result)
                    indexMap[char] = index
                    border2 = index
                else :
                    border1 = indexMap.get(char) + 1
                    border2 = index
                    l = border2 - border1 + 1
                    result = max(l , result)
                    indexMap[char] = index
            index += 1

        return result