Given a string *s*, find the length of the longest substring without repeating characters.
s = "input string"
integer (length of longest unique-character substring)
Example 1:
Input:
s = "abcabcbb"
Output:
3
Explanation:
The longest substring without repeating letters is "abc" of length 3.
Example 2:
Input:
s = "bbbbb"
Output:
1
Explanation:
Longest unique substring is "b" of length 1.