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| -rw-r--r-- | challenge-090/andinus/README | 94 | ||||
| -rw-r--r-- | challenge-090/andinus/README.org | 75 | ||||
| -rw-r--r-- | challenge-090/andinus/blog-2.txt | 1 | ||||
| -rwxr-xr-x | challenge-090/andinus/raku/ch-2.raku | 38 |
4 files changed, 175 insertions, 33 deletions
diff --git a/challenge-090/andinus/README b/challenge-090/andinus/README index b372bec8d3..b662f1cb50 100644 --- a/challenge-090/andinus/README +++ b/challenge-090/andinus/README @@ -1,67 +1,95 @@ ━━━━━━━━━━━━━━━ - CHALLENGE 086 + CHALLENGE 090 Andinus ━━━━━━━━━━━━━━━ - 2020-11-15 + 2020-12-08 Table of Contents ───────────────── -1. Task 1 - Pair Difference -.. 1. Perl +1. Task 2 - Ethiopian Multiplication +.. 1. Raku -1 Task 1 - Pair Difference -══════════════════════════ +1 Task 2 - Ethiopian Multiplication +═══════════════════════════════════ - You are given an array of integers @N and an integer $A. + You are given two positive numbers $A and $B. - Write a script to find find if there exists a pair of elements in the - array whose difference is $A. + Write a script to demonstrate [Ethiopian Multiplication] using the + given numbers. - Print 1 if exists otherwise 0. +[Ethiopian Multiplication] +<https://threesixty360.wordpress.com/2009/06/09/ethiopian-multiplication/> -1.1 Perl +1.1 Raku ──────── - • Program: <file:perl/ch-1.pl> + • Program: <file:perl/ch-2.raku> - @N & $A are taken from stdin, $A is the last argument. + Start by taking `$A' & `$B' which are defined to be `Int' & positive. ┌──── - │ die "usage: ./ch-1.pl <integers \@N> <integer \$A>\n" - │ unless scalar @ARGV >= 3; - │ - │ my $A = pop @ARGV; - │ my @N = @ARGV; + │ sub MAIN ( + │ #= positive numbers + │ Int $A is copy where * > 0, + │ Int $B is copy where * > 0 + │ ) { + │ ... + │ } └──── - We just loop over @N over a loop over @N & find the difference. If - it's equal to `$A' or `-$A' then we print `1' & exit. The first loop - is `shift''ing the numbers out of array `@N' because we are matching - for both `$A' & `-$A' so we don't need the number again. + Here's relevant part from the link that was given above: + Start with the two numbers on top. Halve one, ignoring any + remainders or fractions, and double the other, stopping + when you get to 1. - For example, if `@N = [1, 2]' & we don't `shift' in first loop then - we'll perform 2 subtraction operations: `1 - 2' & `2 - 1' & we won't - have to match for `-$A' but if we just match for `-$A' then we can use - `shift' & we'll only have to perform 1 subtraction operation `1 - 2'. + 14 & 12 7 & 24 3 & 48 [See how I ignored the fact that + halving 7 leaves 1 left over?] 1 & 96 <— Stop here. - We assume subtraction costs more than matching with `-$A', that makes - this more efficient. But it doesn't matter much. + Now look at the numbers on the right. Some are across from + an even number: in this case, 12 is across from the + original 14. Ignore those, and add the rest. So we’ll add + 24, 48, and 96, which were across from odd numbers, and + get 168. And that’s the product! Isn’t that cool? + + We do the same thing & also print the instructions. ┌──── - │ while (my $int = shift @N) { - │ foreach (@N) { - │ my $diff = $int - $_; - │ print "1\n" and exit 0 if ($diff == $A or $diff == -$A); + │ my %sets; + │ + │ say "Ethopian Multiplication.\n"; + │ say "Start with $A, $B."; + │ say "Divide $A by 2 & multiple $B by 2 at each step."; + │ say "Continue until $A equals 1. Drop the remainder, both should be Integer.\n"; + │ + │ say "$A, $B"; + │ while True { + │ %sets{$A} = $B.Int; + │ $A = ($A / 2).Int; + │ $B = ($B * 2).Int; + │ last if $A < 1; + │ say "$A, $B"; + │ } + │ + │ say "\nNow to find the product, simply add all the numbers on right side of ','."; + │ say "But skip those numbers which have an even number on the left side.\n"; + │ + │ my Int $product = 0; + │ for %sets.sort({.key.Int}).reverse -> $pair { + │ if $pair.key % 2 != 0 { + │ $product += $pair.value; + │ say "- Adding ", $pair.value, " to product."; + │ } else { + │ say "- Skipping ", $pair.value, " because ", $pair.key, " is even."; │ } │ } - │ print "0\n"; │ + │ say "\nProduct: $product"; └──── diff --git a/challenge-090/andinus/README.org b/challenge-090/andinus/README.org new file mode 100644 index 0000000000..c4f5da3378 --- /dev/null +++ b/challenge-090/andinus/README.org @@ -0,0 +1,75 @@ +#+SETUPFILE: ~/.emacs.d/org-templates/level-2.org +#+HTML_LINK_UP: ../index.html +#+OPTIONS: toc:2 +#+EXPORT_FILE_NAME: index +#+DATE: 2020-12-08 +#+TITLE: Challenge 090 + +* Task 2 - Ethiopian Multiplication +You are given two positive numbers $A and $B. + +Write a script to demonstrate [[https://threesixty360.wordpress.com/2009/06/09/ethiopian-multiplication/][Ethiopian Multiplication]] using the given +numbers. +** Raku +- Program: [[file:perl/ch-2.raku]] + +Start by taking =$A= & =$B= which are defined to be =Int= & positive. +#+BEGIN_SRC raku +sub MAIN ( + #= positive numbers + Int $A is copy where * > 0, + Int $B is copy where * > 0 +) { + ... +} +#+END_SRC + +Here's relevant part from the link that was given above: +#+BEGIN_QUOTE +Start with the two numbers on top. Halve one, ignoring any remainders or +fractions, and double the other, stopping when you get to 1. + +14 & 12 +7 & 24 +3 & 48 [See how I ignored the fact that halving 7 leaves 1 left over?] +1 & 96 <— Stop here. + +Now look at the numbers on the right. Some are across from an even +number: in this case, 12 is across from the original 14. Ignore those, +and add the rest. So we’ll add 24, 48, and 96, which were across from +odd numbers, and get 168. And that’s the product! Isn’t that cool? +#+END_QUOTE + +We do the same thing & also print the instructions. +#+BEGIN_SRC raku +my %sets; + +say "Ethopian Multiplication.\n"; +say "Start with $A, $B."; +say "Divide $A by 2 & multiple $B by 2 at each step."; +say "Continue until $A equals 1. Drop the remainder, both should be Integer.\n"; + +say "$A, $B"; +while True { + %sets{$A} = $B.Int; + $A = ($A / 2).Int; + $B = ($B * 2).Int; + last if $A < 1; + say "$A, $B"; +} + +say "\nNow to find the product, simply add all the numbers on right side of ','."; +say "But skip those numbers which have an even number on the left side.\n"; + +my Int $product = 0; +for %sets.sort({.key.Int}).reverse -> $pair { + if $pair.key % 2 != 0 { + $product += $pair.value; + say "- Adding ", $pair.value, " to product."; + } else { + say "- Skipping ", $pair.value, " because ", $pair.key, " is even."; + } +} + +say "\nProduct: $product"; +#+END_SRC diff --git a/challenge-090/andinus/blog-2.txt b/challenge-090/andinus/blog-2.txt new file mode 100644 index 0000000000..5b667faed0 --- /dev/null +++ b/challenge-090/andinus/blog-2.txt @@ -0,0 +1 @@ +https://andinus.tilde.institute/pwc/challenge-090/ diff --git a/challenge-090/andinus/raku/ch-2.raku b/challenge-090/andinus/raku/ch-2.raku new file mode 100755 index 0000000000..5a30ae90b4 --- /dev/null +++ b/challenge-090/andinus/raku/ch-2.raku @@ -0,0 +1,38 @@ +#!/usr/bin/env raku + +sub MAIN ( + #= positive numbers + Int $A is copy where * > 0, + Int $B is copy where * > 0 +) { + my %sets; + + say "Ethopian Multiplication.\n"; + say "Start with $A, $B."; + say "Divide $A by 2 & multiple $B by 2 at each step."; + say "Continue until $A equals 1. Drop the remainder, both should be Integer.\n"; + + say "$A, $B"; + while True { + %sets{$A} = $B.Int; + $A = ($A / 2).Int; + $B = ($B * 2).Int; + last if $A < 1; + say "$A, $B"; + } + + say "\nNow to find the product, simply add all the numbers on right side of ','."; + say "But skip those numbers which have an even number on the left side.\n"; + + my Int $product = 0; + for %sets.sort({.key.Int}).reverse -> $pair { + if $pair.key % 2 != 0 { + $product += $pair.value; + say "- Adding ", $pair.value, " to product."; + } else { + say "- Skipping ", $pair.value, " because ", $pair.key, " is even."; + } + } + + say "\nProduct: $product"; +} |