3. Longest Substring Without Repeating Characters

Medium (Trung bình) Python 🔗 Xem trên LeetCode

📋 Đề Bài

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.

🧠 Thuật Toán & Kỹ Thuật

String (Chuỗi)
⏱️ Thời gian O(n)
💾 Không gian O(n)

💻 Lời Giải

Python 0003-longest-substring-without-repeating-characters.py
class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        # "abcabcbb"
        #    ^^^
        # "pwwkew"
        
        maxLen = 0
        setChr = set()
        j = 0
        n = len(s)
        for i in range(n):
            while s[i] in setChr:
                setChr.discard(s[j])
                j += 1
            setChr.add(s[i])
            maxLen = max(maxLen, len(setChr))
            
        return maxLen