3. Longest Substring Without Repeating Characters

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 * 10<sup>4</sup>

• s consists of English letters, digits, symbols and spaces.

Solution:

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        """
        Sliding window method to solve the problem
        """
        charSet = set()
        l = 0
        res = 0

        for r in range(len(s)):
            # check for the duplicate
            while s[r] in charSet:
                # remove if any
                charSet.remove(s[l])
                l += 1
            # add the visited char to set
            charSet.add(s[r])
            # get the max substring
            res = max(res, r-l+1)

        return res