python_important_practice/LongestSubstringWithoutRepeatingCharacters.py at main · dhirajpatra/python_important_practice · GitHub

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"""
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.
"""


class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        max_len = 0
        left = 0
        char_index = {}

        for right in range(len(s)):
            if s[right] in char_index and char_index[s[right]] >= left:
                left = char_index[s[right]] + 1
            char_index[s[right]] = right
            max_len = max(max_len, right - left + 1)

        return max_len


# Example usage
if __name__ == "__main__":
    solution = Solution()
    s = "abcabcbb"
    result = solution.lengthOfLongestSubstring(s)
    print(result)  # Output: 3