Add challenge-086's ch-1 solution in Perl

4 files changed, 134 insertions, 1 deletions

diff --git a/challenge-086/andinus/README b/challenge-086/andinus/README
index 5c0544600b..b372bec8d3 100644
--- a/challenge-086/andinus/README
+++ b/challenge-086/andinus/README
@@ -1 +1,67 @@
-Solutions by Andinus.
+                            ━━━━━━━━━━━━━━━
+                             CHALLENGE 086
+
+                                Andinus
+                            ━━━━━━━━━━━━━━━
+
+
+                               2020-11-15
+
+
+Table of Contents
+─────────────────
+
+1. Task 1 - Pair Difference
+.. 1. Perl
+
+
+
+
+
+1 Task 1 - Pair Difference
+══════════════════════════
+
+  You are given an array of integers @N and an integer $A.
+
+  Write a script to find find if there exists a pair of elements in the
+  array whose difference is $A.
+
+  Print 1 if exists otherwise 0.
+
+
+1.1 Perl
+────────
+
+  • Program: <file:perl/ch-1.pl>
+
+  @N & $A are taken from stdin, $A is the last argument.
+  ┌────
+  │ die "usage: ./ch-1.pl <integers \@N> <integer \$A>\n"
+  │     unless scalar @ARGV >= 3;
+  │
+  │ my $A = pop @ARGV;
+  │ my @N = @ARGV;
+  └────
+
+  We just loop over @N over a loop over @N & find the difference. If
+  it's equal to `$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' & `-$A' so we don't need the number again.
+
+  For example, if `@N = [1, 2]' & we don't `shift' in first loop then
+  we'll perform 2 subtraction operations: `1 - 2' & `2 - 1' & we won't
+  have to match for `-$A' but if we just match for `-$A' then we can use
+  `shift' & we'll only have to perform 1 subtraction operation `1 - 2'.
+
+  We assume subtraction costs more than matching with `-$A', that makes
+  this more efficient. But it doesn't matter much.
+  ┌────
+  │ while (my $int = shift @N) {
+  │     foreach (@N) {
+  │         my $diff = $int - $_;
+  │         print "1\n" and exit 0 if ($diff == $A or $diff == -$A);
+  │     }
+  │ }
+  │ print "0\n";
+  │
+  └────
diff --git a/challenge-086/andinus/README.org b/challenge-086/andinus/README.org
new file mode 100644
index 0000000000..46f1916e57
--- /dev/null
+++ b/challenge-086/andinus/README.org
@@ -0,0 +1,48 @@
+#+SETUPFILE: ~/.emacs.d/org-templates/level-2.org
+#+HTML_LINK_UP: ../../writings/
+#+OPTIONS: toc:2
+#+EXPORT_FILE_NAME: index
+#+DATE: 2020-11-15
+#+TITLE: Challenge 086
+
+* Task 1 - Pair Difference
+You are given an array of integers @N and an integer $A.
+
+Write a script to find find if there exists a pair of elements in the
+array whose difference is $A.
+
+Print 1 if exists otherwise 0.
+** Perl
+- Program: [[file:perl/ch-1.pl]]
+
+@N & $A are taken from stdin, $A is the last argument.
+#+BEGIN_SRC perl
+die "usage: ./ch-1.pl <integers \@N> <integer \$A>\n"
+    unless scalar @ARGV >= 3;
+
+my $A = pop @ARGV;
+my @N = @ARGV;
+#+END_SRC
+
+We just loop over @N over a loop over @N & find the difference. If it's
+equal to =$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= & =-$A= so
+we don't need the number again.
+
+For example, if =@N = [1, 2]= & we don't =shift= in first loop then we'll
+perform 2 subtraction operations: =1 - 2= & =2 - 1= & we won't have to match
+for =-$A= but if we just match for =-$A= then we can use =shift= & we'll only
+have to perform 1 subtraction operation =1 - 2=.
+
+We assume subtraction costs more than matching with =-$A=, that makes this
+more efficient. But it doesn't matter much.
+#+BEGIN_SRC perl
+while (my $int = shift @N) {
+    foreach (@N) {
+        my $diff = $int - $_;
+        print "1\n" and exit 0 if ($diff == $A or $diff == -$A);
+    }
+}
+print "0\n";
+
+#+END_SRC
diff --git a/challenge-086/andinus/blog-1.txt b/challenge-086/andinus/blog-1.txt
new file mode 100644
index 0000000000..67bbe6d0db
--- /dev/null
+++ b/challenge-086/andinus/blog-1.txt
@@ -0,0 +1 @@
+https://andinus.nand.sh/pwc/challenge-086
diff --git a/challenge-086/andinus/perl/ch-01.pl b/challenge-086/andinus/perl/ch-01.pl
new file mode 100755
index 0000000000..37b9a84153
--- /dev/null
+++ b/challenge-086/andinus/perl/ch-01.pl
@@ -0,0 +1,18 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+die "usage: ./ch-1.pl <integers \@N> <integer \$A>\n"
+    unless scalar @ARGV >= 3;
+
+my $A = pop @ARGV;
+my @N = @ARGV;
+
+while (my $int = shift @N) {
+    foreach (@N) {
+        my $diff = $int - $_;
+        print "1\n" and exit 0 if ($diff == $A or $diff == -$A);
+    }
+}
+print "0\n";