Longest Substring Without Repeating Characters

#title
#Longest Substring Without Repeating Characters 
#description:
#Given a string, 
#find the length of the longest substring without 
#repeating characters. For example, 
#the longest substring without repeating letters 
#for "abcabcbb" is "abc", which the length is 3. 
#For "bbbbb" the longest substring is "b", 
#with the length of 1.

# one method:O(n)
# dict.has_key need O(1)
# substring forward a bit each step
# class Solution:
#     # @return an integer
#     def lengthOfLongestSubstring(self, s):
#     	substring = dict()
#     	max_len = 1
#     	min_num = 0
#     	for i in range(len(s)):
#     		if not substring.has_key(s[i]):
#     			substring[s[i]] = i 
#     			if (i + 1 - min_num > max_len):
#     				max_len = i + 1 - min_num
#     		else:
#     			if(substring[s[i]] + 1 > min_num):
#     				min_num = substring[s[i]] + 1
#     			if(substring[s[i]] < min_num):
#     				substring[s[i]] = min_num
#     			if(i - substring[s[i]] > max_len):
#     				max_len = i -substring[s[i]]
#     			substring[s[i]] = i 
#     		print max_len,min_num,substring
#     	return max_len

#method two:need O(n)
#add flag to fore_process 
#and note that print sentence
class Solution:
    # @return an integer
    def lengthOfLongestSubstring(self, s):
    	substring = dict()
    	max_len = 1
    	min_num = 0
    	flag = dict()
    	for i in range(len(s)):
    		flag[s[i]] = 0
    	for i in range(len(s)):
    		if flag[s[i]] == 0:
    			flag[s[i]] = 1
    			substring[s[i]] = i 
    			if (i + 1 - min_num > max_len):
    				max_len = i + 1 - min_num
    		else:
    			if(substring[s[i]] + 1 > min_num):
    				min_num = substring[s[i]] + 1
    			if(substring[s[i]] < min_num):
    				substring[s[i]] = min_num
    			if(i - substring[s[i]] + 1 > max_len):
    				max_len = i + 1 - substring[s[i]]
    			substring[s[i]] = i 
    		# print max_len,min_num,substring
    	if len(s) == 0:
    		max_len = 0
    	return max_len


if __name__ == '__main__':
	s = Solution()
	substring = 'abcabcbb'
	substring = 'bbbbb'
	substring = 'abcabbcaa'
	substring = 'ynqogshxhchhpqhjrwwtdm'
	substring = 'bhhoejpnsoqioadvynqrbo'
#	substring = ''
#	substring = 'tmmzuxt'
	print s.lengthOfLongestSubstring(substring)