Ask HN: How can Google Maps built in URL shortener be so short?

https://news.ycombinator.com/item?id=2938129

by DarkMeld • 15 years ago

5 4 15 years ago

news.ycombinator.com

It looks like it only uses 4 unique characters. (ex. http://g.co/maps/32xe)

chetan51• 15 years ago

It might be incrementally generating codes. So it's only at 4 unique characters because only those many URLs have been generated so far; once all the 4-character codes have been exhausted, it would start using 5-character codes.

mariust• 15 years ago

Or maybe a link expires in a certain amount of time (2-4 months for e.g.) and they start from the start there are quite a few combinations translated in math is something like combinations of 10 (digits) by 28 (letters)

jones1618• 15 years ago

I agree with chetan51. There are 36 ^ 4 = 1,679,616 possible four-character short links. I imagine these are permanent. When they run out, they'll go to 5 for the next 60 million, etc.

jaredsohn• 15 years ago

They probably use less, though. I'm guessing they automatically filter out dictionary words, especially profane ones.

Ask HN: How can Google Maps built in URL shortener be so short?

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