You’re interviewing for a backend or data engineering role at a FAANG-level company. The interviewer describes a real product scenario:
A large streaming, search, or marketplace platform analyzes user interaction logs. Each session produces a string that represents a sequence of actions or identifiers, such as:
- page clicks or feature usage codes
- search query characters typed over time
- event keys in a stream
- tokens in a request trace
To detect healthy behavior patterns and reduce fraud, the platform needs to find the longest continuous segment of activity where no identifier repeats.
The session log is represented as a string s. The platform wants the length of the longest substring that contains no repeating characters.
This is a common practice coding problem for DSA question might ask in Google, Amazon, Netflix, Meta, Apple, Microsoft, Uber, and Bloomberg interviews.
Your Task
Given a string s, return the length of the longest substring without repeating characters.
A substring must be contiguous, meaning characters must come from consecutive positions in the string.
Input Format
s: a string (can include letters, digits, symbols, and spaces)
Output Format
- A single integer representing the maximum length of a substring without repeating characters