Project Euler 17: Count how many letters would be needed to write all the numbers in words from 1 to 1000.
Problem Description
If the numbers 1 to 5 are written out in words: one, two, three, four, five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.
If all the numbers from 1 to 1000 (one thousand) inclusive were written out in words, how many letters would be used?
NOTE: Do not count spaces or hyphens. For example, 342 (three hundred and fortytwo) contains 23 letters and 115 (one hundred and fifteen) contains 20 letters. The use of “and” when writing out numbers is in compliance with British usage.
Analysis
Converted the integers from 1 to 999 to the written equivalent, removed spaces and hyphens, added the character count for each one, including “onethousand”.
Although this is written in the long, lost language of Perl, it is quite extensible for converting a number to its Englishword equivalent. So, instead of solving the problem directly, I wrote this to solve more general problems of similar nature.
Python would also handle this job nicely, but there is still a hopeless romantic attachment to Perl that, I think, I’ll never lose. Hope you enjoy the solution in a throwback language.
Project Euler 17 Solution
Runs < 0.001 seconds in Perl.@D{0 .. 20, 30,40,50,60,70,80,90} = qw
zero one two three four five six seven eight nine ten
eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen
twenty thirty forty fifty sixty seventy eighty ninety;
for $i (1..999) {
$x= num2en($i); $x=~s/[\s\]//g;
$l+= length($x);
}
print "Answer to PE17 = ",$l+length('onethousand');
sub num2en {
my($x) = $_[0];
return $D{$x} if defined $D{$x};
return $D{$1 . '0'} . '' . $D{$2} if( $x =~ m/^(.)(.)$/ );
if ( $x =~ m/^(.)(..)$/ ) {
my($h, $rest) = ("$D{$1} hundred", $2);
return $h if $rest eq '00';
return "$h and " . num2en($rest);
}
}
Use this link to get the Project Euler 17 Solution Perl source.Answer
Slowly swipe from either end beginning with the white vertical bar to get an idea of the starting or ending digits. For less drama, just double click the answer area. The distance between the two bars will give you an idea of the magnitude. Touch devices can tap and hold the center of the box between the two bars and choose define to reveal the answer.Afterthoughts

No afterthoughts yet.
dude when u try to print every number you can see that it doesn’t print “s” letters for example not seven but even. Check it out
You’re awesome Dorian! The backslashes got removed during publishing. I’ve corrected it. So the corrected line should read:
$x=num2en($i); $x=~s/[\s\]//g;
Thanks for being so observant.