534. Design TinyURL
Problem:
How would you design a URL shortening service that is similar to TinyURL?
Background: TinyURL is a URL shortening service where you enter a URL such as https://leetcode.com/problems/design-tinyurl and it returns a short URL such as http://tinyurl.com/4e9iAk.
Requirements: For instance, "http://tinyurl.com/4e9iAk" is the tiny url for the page "https://leetcode.com/problems/design-tinyurl". The identifier (the highlighted part) can be any string with 6 alphanumeric characters containing 0-9, a-z, A-Z. Each shortened URL must be unique; that is, no two different URLs can be shortened to the same URL. Note about Questions: Below are just a small subset of questions to get you started. In real world, there could be many follow ups and questions possible and the discussion is open-ended (No one true or correct way to solve a problem). If you have more ideas or questions, please ask in Discuss and we may compile it here!
Questions:
- How many unique identifiers possible? Will you run out of unique URLs?
- Should the identifier be increment or not? Which is easier to design? Pros and cons?
- Mapping an identifier to an URL and its reversal - Does this problem ring a bell to you?
- How do you store the URLs? Does a simple flat file database work?
- What is the bottleneck of the system? Is it read-heavy or write-heavy?
- Estimate the maximum number of URLs a single machine can store.
- Estimate the maximum number of queries per second (QPS) for decoding a shortened URL in a single machine.
- How would you scale the service? For example, a viral link which is shared in social media could result in a peak QPS at a moment's notice.
- How could you handle redundancy? i,e, if a server is down, how could you ensure the service is still operational?
- Keep URLs forever or prune, pros/cons? How we do pruning? (Contributed by @alex_svetkin)
- What API would you provide to a third-party developer? (Contributed by @alex_svetkin)
- If you can enable caching, what would you cache and what's the expiry time? (Contributed by @Humandroid)
Solutions:
No coding required.