3. 无重复字符的最长子串
class Solution:
def lengthOfLongestSubstring(self, s: str) -> int:
res = 0
visited = list()
for i in range(len(s)):
# 左移窗口
while s[i] in visited: visited.pop(0)
# 右移窗口
visited.append(s[i])
res = max(res, len(visited))
return res
