Merge pull request #2246 from andinus/master

Add challenge-077's ch-1 incomplete solution in Perl

3 files changed, 48 insertions, 72 deletions

diff --git a/challenge-077/andinus/README b/challenge-077/andinus/README
index 1653e8e915..9437e98f28 100644
--- a/challenge-077/andinus/README
+++ b/challenge-077/andinus/README
@@ -1,102 +1,52 @@
                             ━━━━━━━━━━━━━━━
-                             CHALLENGE 076
+                             CHALLENGE 077
                             ━━━━━━━━━━━━━━━
 
 
 Table of Contents
 ─────────────────
 
-1 Task 1 - Prime Sum
+1 Task 1 - Fibonacci Sum
 .. 1.1 Perl
 
 
 
 
 
-1 Task 1 - Prime Sum
-════════════════════
+1 Task 1 - Fibonacci Sum
+════════════════════════
 
-  You are given a number `$N'. Write a script to find the minimum number
-  of prime numbers required, whose summation gives you `$N'.
+  You are given a positive integer `$N'.
 
-  • For the sake of this task, please assume 1 is not a prime number.
+  Write a script to find the total number of Fibonacci Numbers required
+  to get `$N' on addition. You are NOT allowed to repeat a number. Print
+  0 if none found.
+
+  *Note*: This solution is incomplete. Others have pushed complete
+   solutions, look at those.
 
 
 1.1 Perl
 ────────
 
   • Program: [file:perl/ch-1.pl]
-  • Help taken from: [https://stackoverflow.com/a/35756072].
-
-  User input is stored in `$input'.
-  ┌────
-  │ my $input = shift @ARGV;
-  │ chomp $input;
-  └────
-
-  1 is assumed not to be a prime number so we reject numbers less than
-  or equal to 1.
-  ┌────
-  │ die "Invalid input, enter numbers greater than 1.\n" if $input <= 1;
-  └────
-
-  If it's a prime number then the minimum sum is the number itself so we
-  just return it & exit.
-  ┌────
-  │ say $input and exit 0 if is_prime($input) == 1;
-  └────
-
-  If `$input' is even then we loop from 2 to `$input / 2' & check if
-  both `$i' & `$diff' are primes. If both are primes then we have our
-  numbers.
 
-  Eventually we'll find 2 primes to be a sum of even numbers. From
-  WikiPedia, [Goldbach's conjecture] has been shown to hold for all
-  integers less than `4 × 10^18'.
+  Make a list of all possible sums of `$input'.
   ┌────
-  │ if ($input % 2 == 0) {
-  │     foreach my $i (2 ... $input / 2) {
-  │         my $diff = $input - $i;
-  │         say "$i + $diff"
-  │             if is_prime($i) and is_prime($diff);
-  │     }
+  │ my @sums;
+  │ foreach my $num (0 ... $input / 2) {
+  │     my $diff = $input - $num;
+  │     push @sums, [$diff, $num];
   │ }
   └────
 
-  If the input is odd then we first check if `$input - 2' is a prime, if
-  it is then input is the sum of two primes, 2 & `$input - 2'.
+  Loop over `@sums' & then print those sets which have both `$sums->[0]'
+  & `$sums->[1]' in fibonacci series.
   ┌────
-  │ elsif (is_prime($input - 2)) {
-  │     say "2 + $input";
-  │ }
-  └────
-
-  If even that doesn't match then the minimum sum will have three
-  numbers. 3 & then we use the same function as for even numbers to find
-  the other two primes.
-  ┌────
-  │ else {
-  │     foreach my $i (2 ... ($input - 3) / 2) {
-  │         my $diff = $input - 3 - $i;
-  │         say "3 + $i + $diff"
-  │             if is_prime($i) and is_prime($diff);
-  │     }
-  │ }
-  └────
-
-  If $num is divisible by any number between 2 & `sqrt($num)' then it's
-  not prime.
-  ┌────
-  │ sub is_prime {
-  │     my $num = shift @_;
+  │ sub is_fib { return Math::Fibonacci::isfibonacci(@_) }
   │
-  │     foreach my $i (2 ... sqrt($num)) {
-  │         return 0 if $num % $i == 0;
-  │     }
-  │     return 1;
+  │ foreach (@sums) {
+  │     next unless is_fib($_->[0]) and is_fib($_->[1]);
+  │     say "$_->[0] + $_->[1]";
   │ }
   └────
-
-
-[Goldbach's conjecture]
-https://en.wikipedia.org/wiki/Goldbach%2527s_conjecture
diff --git a/challenge-077/andinus/blog-1.txt b/challenge-077/andinus/blog-1.txt
new file mode 100644
index 0000000000..3758cbc1da
--- /dev/null
+++ b/challenge-077/andinus/blog-1.txt
@@ -0,0 +1 @@
+https://andinus.tilde.institute/pwc/challenge-077/
diff --git a/challenge-077/andinus/perl/ch-1.pl b/challenge-077/andinus/perl/ch-1.pl
new file mode 100755
index 0000000000..83a03c6069
--- /dev/null
+++ b/challenge-077/andinus/perl/ch-1.pl
@@ -0,0 +1,25 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use feature 'say';
+
+use Math::Fibonacci;
+
+my $input = shift @ARGV;
+chomp $input;
+
+die "Invalid input, enter numbers greater than 0.\n" if $input < 0;
+
+my @sums;
+foreach my $num (0 ... $input / 2) {
+    my $diff = $input - $num;
+    push @sums, [$diff, $num];
+}
+
+sub is_fib { return Math::Fibonacci::isfibonacci(@_) }
+
+foreach (@sums) {
+    next unless is_fib($_->[0]) and is_fib($_->[1]);
+    say "$_->[0] + $_->[1]";
+}