Longest Substring Without Repeating Characters

03. Longest Substring Without Repeating Characters

Difficulty: Medium

Related Topics: Hash Table, String, Sliding Window

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

Example 1:

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

Example 2:

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

Example 3:

Input: s = “pwwkew” Output: 3 Explanation: The answer is “wke”, with the length of 3. Notice that the answer must be a substring, “pwke” is a subsequence and not a substring.

Code

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        dup = ""
        ans = 0
        for i in range(len(s)):
            if s[i] not in dup:
                dup += s[i]
                ans = max(ans, len(dup))
            else:
                dup += s[i]
                while len(dup) != len(set(dup)):
                    dup = dup[1:]
                    ans = max(ans, len(dup))
        return ans