[leetcode] 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 * 104
• s consists of English letters, digits, symbols and spaces.

 

class Solution(object):
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        used = {} 
        max_length = start = 0 
        for index, char in enumerate(s):
            # 이미 등장했던 문자라면 'start' 위치 갱신 
            if char in used and start <= used[char]: 
                start = used[char] + 1
            else: # 최대 부분 문자열 길이 갱신 
                max_length = max(max_length, index - start +1)
            # 현재 문자 위치 삽입 
            used[char] = index 
        return max_length