

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

It looks like it only uses 4 unique characters. (ex. http://g.co/maps/32xe)
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chetan51
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.

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mariust
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)

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jones1618
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.

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

