Cuban primes: Difference between revisions
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m (→{{header|Wren}}: Minor tidy) |
(→{{header|ALGOL 68}}: Tweaks) |
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=={{header|ALGOL 68}}== |
=={{header|ALGOL 68}}== |
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<syntaxhighlight lang="algol68"> |
<syntaxhighlight lang="algol68"> |
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BEGIN |
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# find some cuban primes (using the definition: a prime p is a cuban prime if # |
# find some cuban primes (using the definition: a prime p is a cuban prime if # |
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# p = n^3 - ( n - 1 )^3 # |
# p = n^3 - ( n - 1 )^3 # |
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# construct a list of the primes # |
# construct a list of the primes # |
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[ 1 : prime count ]INT primes; |
[ 1 : prime count ]INT primes; |
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INT prime pos := LWB primes; |
INT prime pos := LWB primes - 1; |
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FOR s FROM LWB sieve TO UPB sieve DO |
FOR s FROM LWB sieve TO UPB sieve DO |
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IF sieve[ s ] THEN primes[ prime pos |
IF sieve[ s ] THEN primes[ prime pos +:= 1 ] := s FI |
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OD; |
OD; |
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IF ODD p THEN |
IF ODD p THEN |
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# 2 is not a cuban prime so we only test odd numbers # |
# 2 is not a cuban prime so we only test odd numbers # |
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BOOL is prime |
BOOL is prime := TRUE; |
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IF p <= UPB sieve THEN |
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is prime := sieve[ SHORTEN p ] |
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ELSE |
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INT max factor = SHORTEN ENTIER long sqrt( p ); |
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| ⚫ | |||
FOR f FROM LWB primes WHILE is prime AND primes[ f ] <= max factor DO |
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is prime := p MOD primes[ f ] /= 0 |
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OD |
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IF is prime THEN |
IF is prime THEN |
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# have a cuban prime # |
# have a cuban prime # |
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cuban count +:= 1 |
IF ( cuban count +:= 1 ) <= print limit THEN |
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IF cuban count <= print limit THEN |
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# must show this cuban # |
# must show this cuban # |
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STRING p formatted = commatise( p ); |
STRING p formatted = commatise( p ); |
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IF cuban count MOD 10 /= 0 THEN print( ( newline ) ) FI; |
IF cuban count MOD 10 /= 0 THEN print( ( newline ) ) FI; |
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print( ( "The ", commatise( max cuban ), " cuban prime is: ", commatise( final cuban ), newline ) ) |
print( ( "The ", commatise( max cuban ), " cuban prime is: ", commatise( final cuban ), newline ) ) |
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END |
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</syntaxhighlight> |
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{{out}} |
{{out}} |
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<pre> |
<pre> |
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