Skip to content

3. Longest Substring Without Repeating Characters

Difficulty Topics

Description

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.

 

Constraints:

  • 0 <= s.length <= 5 * 104
  • s consists of English letters, digits, symbols and spaces.

Solution

longest-substring-without-repeating-characters.py
class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        seen = set()
        i = 0
        res = 0

        for j, x in enumerate(s):
            while x in seen:
                seen.remove(s[i])
                i += 1

            seen.add(x)

            res = max(res, j - i + 1)

        return res