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 * 104
  • s consists of English letters, digits, symbols and spaces.
SOLUTION:
class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        i = 0
        j = i
        longest = 0
        n = len(s)
        dup = {}
        while j < n:
            if s[j] not in dup:
                dup[s[j]] = j
                j += 1
                longest = max(longest, j - i)
            else:
                i = dup[s[j]] + 1
                j = i
                dup = {}
        return longest

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