3. Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without repeating characters.

Examples

• 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.

• Example 4

Input: s = ""

Output: 0

Constraints:

*0 <= s.length <= 5 * 104

• s consists of English letters, digits, symbols and spaces.