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Re^3: Project Euler (a series of challenging mathematical/computer programming problems)

by radiantmatrix (Parson)
on Feb 07, 2006 at 16:04 UTC ( #528546=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Project Euler (a series of challenging mathematical/computer programming problems)
in thread Project Euler (a series of challenging mathematical/computer programming problems)

No need to reformat, just use the script below to put the large primes file in a DBD::SQLite2 database. First, download and unzip the files that contain the first 15 million primes in chunks of 1 million. You will have primes1.txt through primes15.txt in a directory. Run this there:

#!/bin/perl use strict; use warnings; use DBI; my $dbh = DBI->connect('dbi:SQLite2:dbname=primes.db','','',{RaiseErro +r=>1}); my $cnt = 0; # 'number' has to be text because of length $dbh->do('CREATE TABLE primes (id INTEGER, number TEXT)'); for (1..15) { $cnt = add_primes($dbh,$cnt,"primes$_.txt") } sub add_primes { my ($db, $c, $filename) = @_; open my $file, '<', $filename or die("Can't read '$filename': $!") +; print STDERR "Adding primes from $filename\n"; #first two lines are not data, skip them for (1..2) { <$file> } eval { $db->begin_work; my $sth = $db->prepare('INSERT INTO primes (id,number) VALUES +(?,?)'); while (<$file>) { foreach ( split(/\s+/,$_) ) { $sth->execute(++$cnt,$_) } } $db->commit; }; if ($@) { print STDERR "Died while processing prime #$cnt, with error:\n +$@"; exit; } return $cnt; }

Then you can always ask for the n'th prime with the SQL (? is n)

SELECT number FROM primes WHERE id = ?
<-radiant.matrix->
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