Longest Substring without Repeating Characters

Given a string, str, return the length of the longest substring without repeating characters.

Sample Example 1

Input:

• string = "bbbbbb"

Output: length = 1

Sample Example 2

Input:

• string = "pwwkew"

Output: length = 3

Sample Example 3

Input:

• string = ""

Output: length = 0

Explanation: Empty string passed as an input.