"""
3. Longest Substring Without Repeating Characters
Difficulty: Medium
https://leetcode.com/problems/longest-substring-without-repeating-characters/

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



Example 1:

Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3. Note that
"bca" and "cab" are also correct answers.

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 <= 10^5

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


class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        left = 0
        ans = 0
        window = set()
        for right, c in enumerate(s):
            while c in window:
                window.remove(s[left])
                left += 1
            window.add(c)
            ans = max(ans, right - left + 1)

        return ans