LeetCode-3 Longest Substring Without Repeating Characters

Description

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

Example

Example 1:
Input: “abcabcbb”
Output: 3
Explanation: The answer is “abc”, with the length of 3.

Example 2:
Input: “bbbbb”
Output: 1
Explanation: The answer is “b”, with the length of 1.

Example 3:
Input: “pwwkew”
Output: 3
Explanation: 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.

Submissions

首先由Example 3知题目要求必须是substring,即原字符串中连续的字符串，而subsequence可以不是。

下面是我的解题思路:
采用滑动窗口的形式,从左往右依次遍历字符串s，如果不在temp中，则加入,扩大右边界,如果在temp中，则移除temp中相应的最前面项,左边索引向右移动,即缩小窗口,而k始终保持为temp中最大的字符串个数.重复遍历当前字符,直到左边索引无法再移动,并更新结果k,最后返回k获取结果.如下图(k即图中res):

图片来源:https://github.com/MisterBooo/LeetCodeAnimation

实现代码如下:

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        temp = set()
        i,j,k = 0,0,0
        while i<len(s) and j<len(s):
            if s[i] not in temp:
                temp.add(s[i])
                i+=1
                k=max(k, i - j)
            else:
                temp.remove(s[j])
                j+=1
        return k

Runtime: 84 ms
Memory Usage: 13 MB

来源：CSDN

作者：温暖℡

链接：https://blog.csdn.net/weixin_41875619/article/details/104061119