step 2a : weigh 9-11 against 1-3. if they're the same, we know it's 12. weigh 12 against any of the others to determine if it's lighter or heavier then you're done. if 9-11 was heavier than 1-3, you know that the real one is heavy. weigh 9 against 10. if they're equal 11 is the real one. otherwise, the heavier of 9 and 10 is the real one.

step 2a of your algorithm is not correct. tachyon's right. you'll lose your head--there's an extra weighing here. instead, it should go something like this:

step 2a : weigh 9 against 10. if they're the same, we know it's 11 or twelve. then weigh 9 against 11. if they're the same, we know it's twelve; if they're different, it's 11 and you're done. if 9 and 10 are different, weigh 9 against 11. if they're the same, it's 10; if they're different, it's 9 and you're done.

my logic for this bit, which works under strict and warnings, is

$p[8]==$p[9]?$p[8]==$p[10]?12:11:$p[8]==$p[10]?10:9;

or, building the return matrix and putting it in a sub:

do{([9,10],[11,12])[$p[8]==$p[9]]->[$p[8]==$p[10]]}

which is one char shorter.

~Particle ;Þ

In reply to Re: (GOLF) pearls and perl by particle
in thread (GOLF) pearls and perl by thraxil

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