Sunday Times Teaser 2742 (2015-04-12)

hymn.awk

#!/usr/bin/awk -f

BEGIN {
}

{
	top = $1$2$3;
	mid = $4$5$6;
	bot = $7$8$9;

	if ((top > mid) || (mid > bot)) {
		next;
	}

	if ((top < 100) || (mid < 100) || (bot < 100)) {
		next;
	}

	if ((top > 500) || (mid > 500) || (bot > 500)) {
		next;
	}

	sum_top = $1 + $2 + $3;
	sum_mid = $4 + $5 + $6;
	sum_bot = $7 + $8 + $9;

	if ((sum_top != sum_mid) || (sum_mid != sum_bot)) {
		next;
	}

	mean = (top + mid + bot) / 3;
	if ((top != mean) && (mid != mean) && (bot != mean)) {
		next;
	}

	printf ("%d %d %d\n", top, mid, bot);
}

END {
}

hymn.txt

three three-digit hymn numbers
all <= 500
one is the mean of the others
no digits repeated
for each number: sum of digits is the same

permute.pl

#!/usr/bin/perl

use strict;
use Algorithm::Permute;

Algorithm::Permute::permute {
	print "@ARGV\n";
} @ARGV;