3. Longest Substring Without Repeating Characters

最新推荐文章于 2025-05-18 01:04:12 发布

原创最新推荐文章于 2025-05-18 01:04:12 发布 · 127 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#python #leetcode

python 同时被 2 个专栏收录

60 篇文章

订阅专栏

leetcode

44 篇文章

订阅专栏

本文介绍了一种高效算法，用于寻找给定字符串中最长的无重复字符子串，并提供了Python实现示例。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Given a string, find the length of the longest substring without repeating characters.

Examples:

Given “abcabcbb”, the answer is “abc”, which the length is 3.

Given “bbbbb”, the answer is “b”, with the length of 1.

Given “pwwkew”, the answer is “wke”, with the length of 3. Note that the answer must be a substring, “pwke” is a subsequence and not a substring.

Python:

class Solution(object):
def lengthOfLongestSubstring(self, s):
    """
    :type s: str
    :rtype: int
    """

    left = 0                      # the first place of substring
    ans = 0                       # the length of longest substring            
    last = {}                     # the dict store the last place of string 

    for i in range(len(s)):
        if s[i] in last and last[s[i]] >= left:
            left = last[s[i]] + 1
        last[s[i]] = i
        ans = max(ans, i - left + 1)
    return ans