Project Euler — problem 17
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It has been two weeks since my last post on the 16th Euler problem. Now, since I just need a break after supper, I’m coming the 17th problem.
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.
This looks like a simple one, although patience and carefulness are required. For one-digit numbers, it’s one to nine; for two-digit numbers, it’s ten to nineteen for 10-19 and twenty to ninety-nine for 20-29; for three-digit numbers, it’s some hundred and two-digit numbers. Sounds a pattern, but I’ll sum the letters up simply arithmetically. So enough talking, here comes the solution, ugly but correctly…
1 2 3 4 5 6 7 8 | nletter.single <- nchar(c("one", "two", "three", "four", "five", "six", "seven", "eight", "nine"))
nletter.teen <- nchar(c("ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "ninteen"))
nletter.ty <- nchar(c("twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninty"))
nletter.less100 <- sum(9 * nletter.single) + sum(nletter.teen) + sum(10 * nletter.ty)
nletter.hundreds <- sum(nletter.single) + 9 * nchar("hundred")
nletter.more100 <- 100 * nletter.hundreds + 99 * 9 * nchar("and") + 9 * nletter.less100
result <- nletter.less100 + nletter.more100 + nchar("onethousand")
cat("The result is:", result, "\n") |
Meanwhile, I’m practising another language — perl. So I also came up with one perl script to convert number (1~999) to word. Just for fun!
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 | #!/usr/bin/perl
# number2word.pl by Tony Wei for covert numbers to words
use strict;
use warnings;
use Getopt::Long;
my $NUMBER;
my $opts = GetOptions(
'number|i=i' => \$NUMBER,
);
my %single_number = (
'1' => 'one',
'2' => 'two',
'3' => 'three',
'4' => 'four',
'5' => 'five',
'6' => 'six',
'7' => 'seven',
'8' => 'eight',
'9' => 'nine',
);
my %teen_number = (
'10' => 'ten',
'11' => 'eleven',
'12' => 'twelve',
'13' => 'thirteen',
'14' => 'fourteen',
'15' => 'fifteen',
'16' => 'sixteen',
'17' => 'seventeen',
'18' => 'eightteen',
'19' => 'ninteen',
);
my %ty_number = (
'2' => 'twenty',
'3' => 'thirty',
'4' => 'forty',
'5' => 'fifty',
'6' => 'sixty',
'7' => 'seventy',
'8' => 'eighty',
'9' => 'ninty',
);
if ($NUMBER < 1 || $NUMBER > 999) {
print "$NUMBER is beyond the range of 1~999.\n";
}
else {
my $word;
my @digits = split("", $NUMBER);
if (scalar(@digits) == 1) {
$word = $single_number{$NUMBER};
}
elsif (scalar(@digits) == 2) {
if ($digits[0] == 1) {
$word = $teen_number{$NUMBER};
}
elsif ($digits[1] == 0) {
$word = $ty_number{$digits[0]};
}
else {
$word = $ty_number{$digits[0]}."_".$single_number{$digits[1]};
}
}
else {
if ($digits[1] == 0 && $digits[2] == 0) {
$word = $single_number{$digits[0]}." hundred";
}
else {
$word = $single_number{$digits[0]}." hundred and ";
if ($digits[1] == 0) {
$word = $word.$single_number{$digits[2]};
}
elsif ($digits[1] == 1) {
$word = $word.$teen_number{join("", @digits[1,2])};
}
elsif ($digits[2] == 0) {
$word = $word.$ty_number{$digits[1]};
}
}
else {
$word = $ty_number{$digits[0]}."-".$single_number{$digits[1]};
}
}
else {
if ($digits[1] == 0 && $digits[2] == 0) {
$word = $single_number{$digits[0]}." hundred";
}
else {
$word = $single_number{$digits[0]}." hundred and ";
if ($digits[1] == 0) {
$word = $word.$single_number{$digits[2]};
}
elsif ($digits[1] == 1) {
$word = $word.$teen_number{join("", @digits[1,2])};
}
elsif ($digits[2] == 0) {
$word = $word.$ty_number{$digits[1]};
}
else {
$word = $word.$ty_number{$digits[1]}."-".$single_number{$digits[2]};
}
}
}
print "The word for $NUMBER is '$word'.\n";
} |
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