Penholodigital squares: Difference between revisions
→{{header|Wren}}: Optimized - about 7 x speed up.
(→{{header|Wren}}: Optimized - about 7 x speed up.) |
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{{libheader|Wren-fmt}}
This is limited to base 14 as base 15 would overflow Wren's safe integer limit of 2^53.
Although I'm not quite sure why, it appears that a necessary condition for a number to be a penholodigital square is for its square root to be exactly divisible by the highest prime factor of (base - 1).
<syntaxhighlight lang="ecmascript">import "./math" for Int
import "./fmt" for Conv, Fmt
Line 775 ⟶ 777:
var min = Conv.atoi(digits[0..(b-2)], b).sqrt.ceil
var max = Conv.atoi(digits[(b-2)..0], b).sqrt.floor
var div = Int.primeFactors(b-1)[-1]
for (i in min..max) {
var sq = i * i
▲ if (b == 10 && (sq % 3) != 0) continue
var digs = Int.digits(sq, b)
if (digs.contains(0)) continue
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