Robbie Hatley's solutions, in Perl, for The Weekly Challenge #309.

challenge-309/robbie-hatley/blog.txt

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+https://hatley-software.blogspot.com/2025/02/robbie-hatleys-solutions-in-perl-for_16.html

challenge-309/robbie-hatley/perl/ch-1.pl

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+#!/usr/bin/env perl
+
+=pod
+
+--------------------------------------------------------------------------------------------------------------
+TITLE AND ATTRIBUTION:
+Solutions in Perl for The Weekly Challenge 309-1,
+written by Robbie Hatley on Sun Feb 16, 2025.
+
+--------------------------------------------------------------------------------------------------------------
+PROBLEM DESCRIPTION:
+Task 309-1: Min Gap
+Submitted by: Mohammad Sajid Anwar
+You are given an array of integers, @ints, increasing order.
+Write a script to return the element before which you find the
+smallest gap.
+
+Example #1:
+Input: @ints = (2, 8, 10, 11, 15)
+Output: 11
+ 8 - 2  => 6
+10 - 8  => 2
+11 - 10 => 1
+15 - 11 => 4
+11 is where we found the min gap.
+
+Example #2:
+Input: @ints = (1, 5, 6, 7, 14)
+Output: 6
+ 5 - 1 => 4
+ 6 - 5 => 1
+ 7 - 6 => 1
+14 - 7 => 7
+6 and 7 where we found the min gap, so we pick the first
+instance.
+
+Example #3:
+Input: @ints = (8, 20, 25, 28)
+Output: 28
+ 8 - 20 => 14
+25 - 20 => 5
+28 - 25 => 3
+28 is where we found the min gap.
+
+--------------------------------------------------------------------------------------------------------------
+PROBLEM NOTES:
+I'll use a ranged loop to subtract from each-element-but-the-first the previous element and keep track of the
+element before-which was the smallest gap.
+
+--------------------------------------------------------------------------------------------------------------
+IO NOTES:
+Input is via either built-in variables or via @ARGV. If using @ARGV, provide one argument which must be a
+single-quoted array of increasing arrays of integers, in proper Perl syntax, like so:
+./ch-1.pl '([-18,88,137,148,154,243,363],[3,5,8,13,21,34])'
+
+Output is to STDOUT and will be each input followed by the corresponding output.
+
+=cut
+
+# ------------------------------------------------------------------------------------------------------------
+# PRAGMAS, MODULES, AND SUBS:
+
+   use v5.36;
+   # Which element of an increasing sequence of integers
+   # has the minimum gap from the previous element?
+   sub min_gap ($aref) {
+      my $min_ele = $$aref[1];
+      my $min_gap = $$aref[1] - $$aref[0];
+      for my $i (2..$#$aref) {
+         my $ele = $$aref[$i];
+         my $gap = $$aref[$i] - $$aref[$i-1];
+         if ($gap < $min_gap) {
+            $min_ele = $ele;
+            $min_gap = $gap
+         }
+      }
+      $min_ele;
+   }
+
+# ------------------------------------------------------------------------------------------------------------
+# INPUTS:
+my @arrays = @ARGV ? eval($ARGV[0]) : ([2, 8, 10, 11, 15], [1, 5, 6, 7, 14], [8, 20, 25, 28]);
+#                  Expected outputs :             11              6                      28
+
+# ------------------------------------------------------------------------------------------------------------
+# MAIN BODY OF PROGRAM:
+$"=', ';
+for my $aref (@arrays) {
+   say '';
+   my $mg = min_gap($aref);
+   say "Array = (@$aref)";
+   say "Element with minimum gap from previous = $mg";
+}

challenge-309/robbie-hatley/perl/ch-2.pl

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+#!/usr/bin/env perl
+
+=pod
+
+--------------------------------------------------------------------------------------------------------------
+TITLE AND ATTRIBUTION:
+Solutions in Perl for The Weekly Challenge 309-2,
+written by Robbie Hatley on Sun Feb 16, 2025.
+
+--------------------------------------------------------------------------------------------------------------
+PROBLEM DESCRIPTION:
+Task 309-2: Min Diff
+Submitted by: Mohammad Sajid Anwar
+You are given an array of integers, @ints. Write a script to
+find the minimum difference between any two elements.
+
+Example #1:
+Input: @ints = (1, 5, 8, 9)
+Output: 1
+1, 5 => 5 - 1 => 4
+1, 8 => 8 - 1 => 7
+1, 9 => 9 - 1 => 8
+5, 8 => 8 - 5 => 3
+5, 9 => 9 - 5 => 4
+8, 9 => 9 - 8 => 1
+
+Example #2:
+Input: @ints = (9, 4, 1, 7)
+Output: 2
+9, 4 => 9 - 4 => 5
+9, 1 => 9 - 1 => 8
+9, 7 => 9 - 7 => 2
+4, 1 => 4 - 1 => 3
+4, 7 => 7 - 4 => 3
+1, 7 => 7 - 1 => 6
+
+--------------------------------------------------------------------------------------------------------------
+PROBLEM NOTES:
+I'll use a pair of nested ranged loops to compare each element to those after it, and return the minimum of
+the absolute values of the differences.
+
+--------------------------------------------------------------------------------------------------------------
+IO NOTES:
+Input is via either built-in variables or via @ARGV. If using @ARGV, provide one argument which must be a
+single-quoted array of arrays of real numbers, in proper Perl syntax, like so:
+./ch-2.pl '([88.2,37.4,-148.9,243.8,36.3],[-40,20,-20,0,40])'
+
+Output is to STDOUT and will be each input followed by the corresponding output.
+
+=cut
+
+# ------------------------------------------------------------------------------------------------------------
+# PRAGMAS, MODULES, AND SUBS:
+
+   use v5.36;
+   use List::Util 'min';
+   # What is the minimum difference between any
+   # two elements of an an array of real numbers?
+   sub min_diff ($aref) {
+      my @diff = ();
+      for my $i (0..$#$aref-1) {
+         for my $j ($i+1..$#$aref) {
+            push @diff, abs $$aref[$i]-$$aref[$j];
+         }
+      }
+      min @diff;
+   }
+
+# ------------------------------------------------------------------------------------------------------------
+# INPUTS:
+my @arrays = @ARGV ? eval($ARGV[0]) : ([1,5,8,9],[9,4,1,7]);
+
+# ------------------------------------------------------------------------------------------------------------
+# MAIN BODY OF PROGRAM:
+$"=', ';
+for my $aref (@arrays) {
+   say '';
+   my $md = min_diff ($aref);
+   say "Array = (@$aref)";
+   say "min diff = $md";
+}