Longest Substring Without Repeating Characters: coding question

Problem

You get a string s. Return the length of the longest substring of s that has no repeated characters.

A substring is a part of the string with consecutive characters. For example, "ell" is a substring of "hello", but "hlo" is not.

Input:: s = "tmmzuxt"
Output:: 5
Explanation:: The substring "mzuxt" has 5 different characters. Each longer substring repeats a character.

Input:: s = "pq rp"
Output:: 4
Explanation:: The space is also a character. The substring "q rp" has 4 different characters.

SysRound wrote this statement. A reference solution checks every example.

Continue with questions that share topics or the same question type.

Longest Substring with At Most K Distinct Characters
Coding · Hash Table · Sliding Window · String
Longest Repeating Character Replacement
Coding · Hash Table · Sliding Window · String
Maximum Number of Occurrences of a Substring
Coding · Hash Table · Sliding Window · String
Minimum Window Substring
Coding · Hash Table · Sliding Window · String

Sources · 2 references

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Amazon
Leetcode 3. Longest Substring Without Repeating Characters
Reported Oct 1, 2026 · 2 source reports
MID_LEVEL
Source snapshot: Nov 12, 2026
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Apple
Leetcode 3. Longest Substring Without Repeating Characters
Reported May 17, 2026 · 2 source reports
MANAGER, MID_LEVEL
Source snapshot: Nov 12, 2026
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Autodesk
Leetcode 3. Longest Substring Without Repeating Characters
Reported May 4, 2026 · 1 source report
SENIOR
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Expedia
Leetcode 3. Longest Substring Without Repeating Characters
Reported Dec 11, 2025 · 1 source report
MID_LEVEL

Problem

You get a string s. Return the length of the longest substring of s that has no repeated characters.

A substring is a part of the string with consecutive characters. For example, "ell" is a substring of "hello", but "hlo" is not.

Input:: s = "tmmzuxt"
Output:: 5
Explanation:: The substring "mzuxt" has 5 different characters. Each longer substring repeats a character.

Input:: s = "pq rp"
Output:: 4
Explanation:: The space is also a character. The substring "q rp" has 4 different characters.

SysRound wrote this statement. A reference solution checks every example.