**Soure Url**: https://leetcode.com/problems/longest-substring-without-repeating-characters/

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

Example 1:

Input:“abcabcbb”

Output:3

Explanation:The answer is`"abc"`

, with the length of 3.Example 2:

Input:“bbbbb”

Output:1

Explanation:The answer is`"b"`

, with the length of 1.Example 3:

Input:“pwwkew”

Output:3

Explanation:The answer is`"wke"`

, with the length of 3.

Note that the answer must be asubstring,`"pwke"`

is asubsequenceand not a substring.