Longest Substring Without Repeating Characters

Given a string s, your task is to compute the length of the longest substring which does not contain any repeating characters.

You are required to approach this problem using an efficient algorithm with a time complexity of \(O(n)\), where \(n\) is the length of the input string. The typical approach is to use a sliding window mechanism with a hash map (or equivalent) to track the last seen position of each character.

This problem is fundamental in understanding the sliding window technique and hash-based lookup for substring problems.

inputFormat

The input consists of a single line, containing the string s. The string may contain letters, digits, and other printable characters. It can also be an empty string.

outputFormat

Output a single integer, which is the length of the longest substring of s that contains no repeated characters.

abcabcbb

3