【leetcode】无重复字符的最长子串（Longest Substring Without Repeating Characters）【python】

左手的ㄟ右手 2022-05-13 22:36 75阅读 0赞

![这里写图片描述][70]  
题目链接：[无重复字符的最长子串][Link 1]

## python ##

class Solution:
        def lengthOfLongestSubstring(self, s):
            """ :type s: str :rtype: int """
            max = 0
            a = [0] * 200
            for i in range(len(s)):
                for j in range(i, len(s)):
                    a[ord(s[j]) - ord('!')] += 1
                    if a[ord(s[j]) - ord('!')] >= 2:
                        local_max = j - i
                        # print('local_max %d' % local_max)
                        a = [0] * 200
                        if local_max > max:
                            max = local_max
                        break
                    elif j == len(s) - 1:
                        print(j)
                        local_max = j - i + 1
                        a = [0] * 200
                        if local_max > max:
                            max = local_max
            if s == " ":
                max = 1
            return max
    
    
    s = 'c'
    sol = Solution()
    print(sol.lengthOfLongestSubstring(s))

--------------------

**使用hash表来存取重复项**  
**注意两种边界情况：第一是一直遍历到末尾都未找到重复项，需要单独统计**  
**第二是字符串可能为空，这个时候，长度为1**  
**需要特别注意的是，字符串不止都是字母，因此需要从‘！’开始计算**  
**python处理ascii的时候，需要用到内置的ord函数！！！！！！！！！！！！！！！！！！**

[70]: /images/20220514/be9a8c07c3364534924f2ff64c353d4c.png
[Link 1]: https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/description/