Longest Substring Without Repeating Characters
Updated Jan 31, 2026
Problem
Given a string s, find the length of the longest substring without repeating characters.
Constraints
0 <= s.length <= 5 * 10^4
s consists of English letters, digits, symbols and spaces.
Examples
Example 1
Input:
s = "abcabcbb"
Output:
3
The answer is "abc", with the length of 3.
Example 2
Input:
s = "bbbbb"
Output:
1
The answer is "b", with the length of 1.
Example 3
Input:
s = "pwwkew"
Output:
3
The answer is "wke", with the length of 3.
Function Signature
def lengthOfLongestSubstring(self, s: str) -> int
How to Submit
Implement a Solution class with a lengthOfLongestSubstring method.
Your method will be called with the input parameters and should return the answer.