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 * 104s consists of English letters, digits, symbols and spaces.