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

[Anonymous Monk]

i'm pretty sure my answer for 112 is correct, but apparently it's not. anybody see anything wrong with this? it works fine for the two examples (.5->538, .9->21780).

my $max    = .99;
my $bouncy = 0;

for (my $n=1; ; $n++)
{
  my ($inc, $dec) = (0, 0);

  my @d = split //, $n;
  for (my $i=0; $i<@d-1; $i++)
  {
    if    ($d[$i] < $d[$i+1]) { $inc++ }
    elsif ($d[$i] > $d[$i+1]) { $dec++ }
  }
  $bouncy++ if $inc and $dec;

  next if $max > $bouncy/$n;  
  printf "n=%d: %%%f\n", $n, $bouncy/$n;   
  last;
}

[hv]

Even though I can't see it explicitly stated anywhere, I think the intention of the site is that you solve the problems on your own without asking for help.

For what it's worth, while working through the problems I found that at least 75% of the time if my first attempt at an answer was wrong it was because I had misread the question rather than because I had a bug in my code.

Hugo

[mpolo]

Well, I don't think that directly helping would be "ethical", but for what it's worth I (and most of the successful coders from what I remember in the fora) did that one with a rather different approach. One helpful trick is to try the examples in the problem (just insert a print "helpful debugging stuff\n" if $n==number_with_known_property; and see if they get classified correctly by your program. Much more fun is number 113, which has a slick mathematical solution, or my methodical number-crunching solution...