Longest Without Repeating 25 XP Medium

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

s = 'abcabcbb'
# Output: 3
# 'abc' is the longest without repeats

This is a variable-size sliding window problem. Expand the right boundary. When a duplicate is found, shrink the left boundary until the duplicate is removed.

Use a set to track characters in the current window. Time: O(n), Space: O(min(n, alphabet)).

📋 Instructions

Implement `length_of_longest_substring(s)` using a sliding window with a set. Test with: - `'abcabcbb'` → 3 - `'bbbbb'` → 1 - `'pwwkew'` → 3 Print all three results.

Use a left pointer and a set. For each right char: while char is in set, remove s[left] from set and move left forward. Add s[right] to set. Track max window size.

🧪 Test Cases

Input

length_of_longest_substring('abcabcbb')

Expected

3

Test case 1

Input

length_of_longest_substring('bbbbb')

Expected

1

Test case 2

Input

length_of_longest_substring('pwwkew')

Expected

3

Test case 3

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main.py

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Output

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