Question

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

Examples:
Given "abcabcbb", the answer is "abc", which the length is 3.
Given "bbbbb", the answer is "b", with the length of 1.
Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

Answer 1

The problem involves finding the longest substring without repeated characters in a given string by using a sliding window technique that keeps track of unique characters.

Step-by-step explanation:

The question is about finding the length of the longest substring in a given string where no characters are repeated. It's important to understand the difference between a substring and a subsequence. A substring is a contiguous sequence of characters within a string, while a subsequence may contain non-adjacent characters taken from the string while maintaining their original order.

To solve this problem algorithmically, a common approach is to use a sliding window technique that involves iterating through the string while maintaining a set to track characters in the current substring. Move the right pointer to expand the window until you encounter a repeating character. If a repeat is detected, shift the left pointer to reduce the window until the repeat no longer exists within it. The length of the longest substring is the maximum size the window reaches during this process.

Here are solutions for the given examples:

• For "abcabcbb", the longest substring without repeating characters is "abc", so the answer is 3.
• For "bbbbb", it's "b" since all characters are repeating, making the answer 1.
• For "pwwkew", the longest substring is "wke", giving us 3 as the answer.