Merge pull request #7669 from mattneleigh/pwc206

	new file:   challenge-206/mattneleigh/perl/ch-1.pl

2 files changed, 211 insertions, 0 deletions

diff --git a/challenge-206/mattneleigh/perl/ch-1.pl b/challenge-206/mattneleigh/perl/ch-1.pl
new file mode 100755
index 0000000000..aae8f60a73
--- /dev/null
+++ b/challenge-206/mattneleigh/perl/ch-1.pl
@@ -0,0 +1,121 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use English;
+
+use List::Util qw(min);
+
+################################################################################
+# Begin main execution
+################################################################################
+
+my @time_lists = (
+    [ "00:00", "23:55", "20:00" ],
+    [ "01:01", "00:50", "00:57" ],
+    [ "10:10", "09:30", "09:00", "09:55" ]
+);
+
+print("\n");
+foreach my $time_list (@time_lists){
+    printf(
+        "Input: \@time = (%s)\nOutput: %d\n\n",
+        join(", ", map("\"$_\"", @{$time_list})),
+        shortest_time_interval_in_list(@{$time_list})
+    );
+}
+
+exit(0);
+################################################################################
+# End main execution; subroutines follow
+################################################################################
+
+
+
+################################################################################
+# Calculate the shortest interval between any two times in HH:MM format within
+# a list, in minutes.  Note that the shortest interval may pass through
+# midnight (00:00); if so, this function does not report that this was the
+# case.  The order in which the times appear in the list does not affect the
+# calculation, and the shortest time may not be between adjacent members of
+# the list; this function does not report between which times the calculated
+# interval occurred.
+# Takes one argument:
+# * The list of times to examine
+# Returns:
+# * The shortest interval between the various times n the list, in minutes; see
+#   notes above
+################################################################################
+sub shortest_time_interval_in_list{
+
+    return(
+        # min() is from List::Util
+        min(
+            # Get a list of intervals between all times
+            # in the argument list- do this with nested
+            # calls to map() in which $i and the inner
+            # $_ will, as array indices, refer to all
+            # pairs in the list
+            map(
+                {
+                    # Capture the outer $_
+                    my $i = $_;
+
+                    map(
+                        calculate_time_interval_pair(
+                            $ARG[$i],
+                            $ARG[$_]
+                        ),
+                        ($i + 1) .. $#ARG
+                    );
+                }
+                0 .. ($#ARG - 1)
+            )
+        )
+    );
+
+}
+
+
+
+################################################################################
+# Calculate the shortest inverval, in minutes, between two times in HH:MM
+# format.  Note that the shortest interval may pass through midnight (00:00);
+# if so, this function does not report that this was the case.  The order in
+# which the arguments appear does not affect the calculation.
+# Takes two arguments:
+# * The first time to examine
+# * The second time to examine
+# Returns:
+# * The time interval between the specified times, in minutes; see notes above
+################################################################################
+sub calculate_time_interval_pair{
+    my $a = shift();
+    my $b = shift();
+
+    # Convert HH:MM format to minutes since
+    # midnight
+    $a =~ m/^(\d+):(\d+)$/;
+    $a = 60 * $1 + $2;
+    $b =~ m/^(\d+):(\d+)$/;
+    $b = 60 * $1 + $2;
+
+    # Make sure $b is larger than $a
+    ($b, $a) = ($a, $b)
+        if($a > $b);
+
+    # Return the minimum of the two possible
+    # distances between the two times.  1440
+    # is the number of minutes in a day;
+    # min() is from List::Util
+    return(
+        min(
+            ($b - $a),
+            (1440 - $b + $a)
+        )
+    );
+
+}
+
+
+
diff --git a/challenge-206/mattneleigh/perl/ch-2.pl b/challenge-206/mattneleigh/perl/ch-2.pl
new file mode 100755
index 0000000000..50753d2ece
--- /dev/null
+++ b/challenge-206/mattneleigh/perl/ch-2.pl
@@ -0,0 +1,90 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use English;
+
+use List::Util qw(min max);
+
+################################################################################
+# Begin main execution
+################################################################################
+
+my @lists = (
+    [ 1, 2, 3, 4 ],
+    [ 0, 2, 1, 3 ]
+);
+
+print("\n");
+foreach my $list (@lists){
+    printf(
+        "Input: \@array = (%s)\nOutput: %d\n\n",
+        join(", ", @{$list}),
+        max_sum_of_pair_mins(@{$list})
+    );
+}
+
+
+exit(0);
+################################################################################
+# End main execution; subroutines follow
+################################################################################
+
+
+
+################################################################################
+# Determine the maximum of the sums of the minimums of each set of pairs within
+# an array holding an even quantity of numbers
+# Takes one argument:
+# * An array of numbers with an even number of members
+# Returns on success:
+# * The maximum of the sums of the minimum values in each pair within the array
+# Returns on error:
+# * undef if the array has an odd number of members
+################################################################################
+sub max_sum_of_pair_mins{
+
+    my @pairs;
+
+    return(undef)
+        if(scalar(@ARG) % 2);
+
+    # Grab a list of all possible pairs within
+    # the given array; do this with nested calls
+    # to map() in which $i and the inner $_ will,
+    # as array indices, refer to all pairs
+    @pairs = map(
+        {
+            # Capture the outer $_
+            my $i = $_;
+
+            map(
+                [ $ARG[$i], $ARG[$_] ],
+                ($i + 1) .. $#ARG
+            );
+        }
+        0 .. ($#ARG - 1)
+    );
+
+    # max() and min() are from List::Util
+    return(
+        # (2) ...then find the maximum value in
+        # that list
+        max(
+            # (1) Generate a list of the sums of the
+            # minima from each pair of pairs...
+            map(
+                (
+                    min(@{$pairs[$_]})
+                    +
+                    min(@{$pairs[$#pairs - $_]})
+                ),
+                0 .. ($#pairs / 2)
+            )
+        )
+    );
+
+}
+
+
+