Substring primes: Difference between revisions
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m (→Using a limit: Replaced getDigits function with a more recently added library function.) |
(→{{header|ALGOL 68}}: Use ALGOL 68-primes) |
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=={{header|ALGOL 68}}== |
=={{header|ALGOL 68}}== |
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{{libheader|ALGOL 68-primes}} |
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<lang algol68>BEGIN # find primes where all substrings of the digits are prime # |
<lang algol68>BEGIN # find primes where all substrings of the digits are prime # |
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# reurns a sieve of primes up to n # |
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PROC sieve = ( INT n )[]BOOL: |
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BEGIN |
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[ 1 : n ]BOOL p; |
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p[ 1 ] := FALSE; p[ 2 ] := TRUE; |
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FOR i FROM 3 BY 2 TO n DO p[ i ] := TRUE OD; |
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FOR i FROM 4 BY 2 TO n DO p[ i ] := FALSE OD; |
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FOR i FROM 3 BY 2 TO ENTIER sqrt( n ) DO |
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IF p[ i ] THEN FOR s FROM i * i BY i + i TO n DO p[ s ] := FALSE OD FI |
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OD; |
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p |
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END # prime list # ; |
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# find the primes of interest # |
# find the primes of interest # |
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PR read "primes.incl.a68" PR |
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INT max number = 500; |
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[]BOOL prime = |
[]BOOL prime = PRIMESIEVE 500; |
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FOR p TO UPB prime DO |
FOR p TO UPB prime DO |
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IF prime[ p ] THEN |
IF prime[ p ] THEN |
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INT d := 10; |
INT d := 10; |
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BOOL is substring := TRUE; |
BOOL is substring := TRUE; |
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WHILE is substring AND d <= |
WHILE is substring AND d <= UPB prime DO |
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INT n := p; |
INT n := p; |
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WHILE is substring AND n > 0 DO |
WHILE is substring AND n > 0 DO |
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