✨ [q3/README]

Author: enkr1

3/README.md

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+https://leetcode.com/problems/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.