Medium
Given a string s, find the length of the longest substring without repeating characters.
Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.
Input: s = "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.
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.
Input: s = ""
Output: 0
- 0 <= s.length <= 5 * 104
- s consists of English letters, digits, symbols and spaces.