Truncatable primes: Difference between revisions
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CoffeeScript |
→{{header|CoffeeScript}}: refactor |
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=={{header|CoffeeScript}}==
<lang coffeescript># You could have symmetric algorithms for max right and left
# truncatable numbers, but they lend themselves to slightly
# different optimizations.
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# the 10 possibilities for the last digit.
if n < 10
while candidate > 0▼
return candidate if f(candidate)▼
candidate -= 1▼
else
left = Math.floor n / 10
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left -= 1
right = 9
throw Error "none found"
max_left_truncatable_number = (max, f) ->
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n -= 1
throw Error "none found"
▲ while candidate > 0
▲ return candidate if f(candidate)
▲ candidate -= 1
is_prime = (n) ->
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