#13MediumDesign· ID Generation and Base62 Encoding

Design a URL Shortener

Design the core of a URL-shortening service: a codec that turns long URLs into short ones and back. Implement the class `Codec`: - `encode(longUrl)` returns a short URL of the form `https://s.example/<code>`, where `<code>` contains only the 62 characters `0-9`, `a-z`, `A-Z`. - `decode(shortUrl)` returns the original long URL for a short URL previously produced by the same `Codec` instance. Different long URLs must never receive the same short URL. Encoding the same long URL twice may return the same or a different short URL, as long as both decode correctly. Your design should be deterministic (no randomness), so the same sequence of calls always yields the same codes. **Test format.** The judge creates one `Codec`, encodes every URL in `urls` in order, then decodes each resulting short URL. The output has one boolean per URL: whether `decode(encode(url))` returned exactly `url`.

Input format

urls: array of URL strings

Output format

Array of booleans, one per URL, true when the round trip returns the original URL

Examples

Input: urls = ["https://example.com/docs/getting-started"]

Output: [true]

The URL receives the code for ID 1 and decodes back to itself.

Input: urls = ["https://example.net/same", "https://example.net/same"]

Output: [true, true]

Encoding the same URL twice returns the same short URL, and both decode correctly.

Constraints

1 <= urls.length <= 10^4
1 <= urls[i].length <= 10^4
Each URL is a valid absolute URL.
Short codes must use only base62 characters.

Study first

#design
#hash-table
#base62
#url-shortener