边工作边刷题：70天一遍leetcode: day 71

Longest Substring with At Most Two Distinct Characters

# Given a string, find the length of the longest substring T that contains at most 2 distinct characters.
# For example, Given s = “eceba”,
# T is "ece" which its length is 3.
# Hide Company Tags Google
# Hide Tags Hash Table Two Pointers String
# Hide Similar Problems (M) Longest Substring Without Repeating Characters (H) Sliding Window Maximum (H) Longest Substring with At Most K Distinct Characters
class Solution(object):
    def lengthOfLongestSubstringTwoDistinct(self, s):
        """
        :type s: str
        :rtype: int
        """
        char1, right1, char2, right2 = '', 0, '', 0
        start = 0
        longest = 0
        for i, c in enumerate(s):
            if not char1 or char1==c:
                char1=c
                right1=i
            elif not char2 or char2==c:
                char2=c
                right2=i
            else:
                # print i
                if right1<right2:
                    char1 = c
                    start=right1+1
                    right1 = i
                else:
                    char2 = c
                    start=right2+1
                    right2 = i
            #print 'i={},start={},right1={},righ2={}'.format(i,start,right1,right2)
            longest = max(longest, i-start+1)
        return longest
sol = Solution()
assert sol.lengthOfLongestSubstringTwoDistinct("cdaba")==3