159 - Longest Substring with At Most Two Distinct Characters
Written on November 5, 2015
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Given a string, find the length of the longest substring T that contains at most 2 distinct characters.
from collections import defaultdict
class Solution:
def lengthOfLongestSubstringTwoDistinct(self, s: str) -> int:
if not s:
return 0
ret = start = 0
char_map = defaultdict(int)
for i, c in enumerate(s):
char_map[c] += 1
while len(char_map) > 2:
char_map[s[start]] -= 1
if char_map[s[start]] == 0:
del char_map[s[start]]
start += 1
ret = max(ret, i - start + 1)
return ret
