Longest substring without repeating characters

Problem Given a string, find the length of the longest contiguous substring that contains no repeated character.

Input / Output

• Input: a string s.
• Output: the length of the longest substring without repeating characters.

Constraints

• Aim for O(n) time.
• s may contain any characters (letters, digits, symbols); the empty string returns 0.

Example

• "abcabcbb" -> 3 ("abc")
• "bbbbb" -> 1 ("b")
• "pwwkew" -> 3 ("wke")