- Added solutions by Colin Crain.

4 files changed, 337 insertions, 0 deletions

diff --git a/challenge-078/colin-crain/perl/ch-1.pl b/challenge-078/colin-crain/perl/ch-1.pl
new file mode 100644
index 0000000000..a36ff8652d
--- /dev/null
+++ b/challenge-078/colin-crain/perl/ch-1.pl
@@ -0,0 +1,64 @@
+#! /opt/local/bin/perl
+#
+#       follow_the_leader.pl
+#
+#         TASK #1 › Leader Element
+#         Submitted by: Mohammad S Anwar
+#         You are given an array @A containing distinct integers.
+# 
+#         Write a script to find all leader elements in the array @A. Print (0)
+#         if none found.
+# 
+#         An element is leader if it is greater than all the elements to its
+#         right side.
+# 
+#         Example 1:
+#             Input: @A = (9, 10, 7, 5, 6, 1)
+#             Output: (10, 7, 6, 1)
+#         Example 2:
+#             Input: @A = (3, 4, 5)
+#             Output: (5)
+# 
+#         method: 
+#             working from the end, the tail element is by definition the
+#             "leader" of none. From there a running local maximum is
+#             established among elements already seen and the focus moves one
+#             element to the left. If the element is greater than the local
+#             maximum, it is the leader and becomes the new maximum. It is also
+#             unshifted onto the front of the output array.
+#         
+#
+#       2020 colin crain
+## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##
+
+
+
+use warnings;
+use strict;
+use feature ":5.26";
+
+## ## ## ## ## MAIN:
+
+my @input = @ARGV;
+@input = (9, 10, 7, 5, 6, 1) if scalar @ARGV == 0;
+say "input:  (", (join ', ', @input), ")";
+
+
+my @output = my ($max) = (pop @input);
+
+while (@input) {
+    my $ele = pop @input;
+    if ($ele > $max) {
+        $max = $ele;
+        unshift @output, $ele;
+    }
+}
+say "output: (", (join ', ', @output), ")";
+
+
+
+
+
+
+
+## ## ## ## ## SUBS:
diff --git a/challenge-078/colin-crain/perl/ch-2.pl b/challenge-078/colin-crain/perl/ch-2.pl
new file mode 100644
index 0000000000..cd07ef3383
--- /dev/null
+++ b/challenge-078/colin-crain/perl/ch-2.pl
@@ -0,0 +1,119 @@
+#! /opt/local/bin/perl
+#
+#       swing_to_the_left.pl
+#
+#         TASK #2 › Left Rotation
+#         Submitted by: Mohammad S Anwar
+#         You are given array @A containing positive numbers and @B containing
+#         one or more indices from the array @A.
+# 
+#         Write a script to left rotate @A so that the number at the first index
+#         of @B becomes the first element in the array. Similary, left rotate @A
+#         again so that the number at the second index of @B becomes the first
+#         element in the array.
+# 
+#         Example 1:
+#             Input:
+#                 @A = (10 20 30 40 50)
+#                 @B = (3 4)
+# 
+#         Explanation:
+#             a) We left rotate the 3rd index element (40) in the @A to make it 0th
+#             index member in the array.
+#                 [40 50 10 20 30]
+# 
+#             b) We left rotate the 4th index element (50) in the @A to make it 0th
+#             index member in the array.
+#                 [50 10 20 30 40]
+# 
+#         Output:
+#             [40 50 10 20 30]
+#             [50 10 20 30 40]
+# 
+#         Example 2:
+# 
+#         Input:
+#             @A = (7 4 2 6 3)
+#             @B = (1 3 4)
+# 
+#         Explanation:
+#             a) We left rotate the 1st index element (4) in the @A to make it
+#             0th index member in the array.
+#                 [4 2 6 3 7]
+# 
+#             b) We left rotate the 3rd index element (6) in the @A to make it
+#             0th index member in the array.
+#                 [6 3 7 4 2]
+# 
+#             c) We left rotate the 4th index element (3) in the @A to make it
+#             0th index member in the array.
+#                 [3 7 4 2 6]
+# 
+#         Output:
+#             [4 2 6 3 7]
+#             [6 3 7 5 2]
+#             [3 7 4 2 6]
+
+#         ----------------------------------------
+#
+#         method:
+#             I'm not sure "rotate" is exactly the right word for whats being
+#             asked for here, but rather what we are being asked to do is to
+#             produce the output as though the array had been rotated. The
+#             distinction is important as we need to retain the integrety of the
+#             original array and perform multiple transformations for output, as
+#             the transformations are not consecutivly applied in a churning
+#             fashion, but rather different applications to the atarting
+#             sequence.
+# 
+#             The new sequences rearrange the elements such that the the tail of
+#             the array, starting at the indicated element, becomes the head,
+#             and the head, up to the break, becomes the tail. This can be done
+#             easily with array slices.
+# 
+#             As removing the head element and placing it on the end is the act
+#             of a left rotation, this is the same action moving a block of
+#             elements simultaniously rather than individual elements
+#             sequentially. In this sense it satisfies both the function and the
+#             spirit of the challenge.
+#             
+# 
+# 
+#       2020 colin crain
+## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##
+
+
+
+use warnings;
+use strict;
+use feature ":5.26";
+
+## ## ## ## ## MAIN:
+
+
+my @array = (7, 4, 2, 6, 3);
+my @idxs  = (1, 3, 0, 4);
+my @output;
+my $end = scalar @array - 1;
+
+for my $idx (@idxs) {
+    $idx == 0 and do {(push @output, \@array); next};
+    my @shifted = @array[$idx..$end, 0..$idx-1];
+    push @output,  \@shifted ;
+}
+
+say "array:      (", (join ', ', @array), ")";
+say "index list: (", (join ', ', @idxs ), ")\n";
+
+say "[", (join ' ', $_->@*), "]" for @output;
+
+
+
+
+
+
+
+
+
+
+## ## ## ## ## SUBS:
diff --git a/challenge-078/colin-crain/raku/ch-1.raku b/challenge-078/colin-crain/raku/ch-1.raku
new file mode 100644
index 0000000000..e528ed3e06
--- /dev/null
+++ b/challenge-078/colin-crain/raku/ch-1.raku
@@ -0,0 +1,51 @@
+#!/usr/bin/env perl6
+# 
+#
+#       follow-the-leader.raku
+#
+#         TASK #1 › Leader Element
+#         Submitted by: Mohammad S Anwar
+#         You are given an array @A containing distinct integers.
+# 
+#         Write a script to find all leader elements in the array @A. Print (0)
+#         if none found.
+# 
+#         An element is leader if it is greater than all the elements to its
+#         right side.
+# 
+#         Example 1:
+#             Input: @A = (9, 10, 7, 5, 6, 1)
+#             Output: (10, 7, 6, 1)
+#         Example 2:
+#             Input: @A = (3, 4, 5)
+#             Output: (5)
+# 
+#         method: working from the end, the tail element is by definition the
+#             "leader" of none. From there a running local maximum is
+#             established among elements already seen and the focus moves one
+#             element to the left. If the element is greater than the local
+#             maximum, it is the leader and becomes the new maximum. Leaders are
+#             propgated to the output array, which needs to be revered back to 
+# 
+#
+#       2020 colin crain
+## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##
+
+
+
+unit sub MAIN (*@input) ;
+
+## in
+@input.elems == 0 and @input = 9, 10, 7, 5, 6, 1;
+
+## work
+my $max = -Inf;
+my @output = @input.reverse
+                   .map( { $_ > $max ?? ($max = $_) !! Nil } )
+                   .grep( *.defined );
+@output .= reverse;
+
+## out
+say " input: ", @input;
+say "output: ", @output;
+
diff --git a/challenge-078/colin-crain/raku/ch-2.raku b/challenge-078/colin-crain/raku/ch-2.raku
new file mode 100644
index 0000000000..c491571918
--- /dev/null
+++ b/challenge-078/colin-crain/raku/ch-2.raku
@@ -0,0 +1,103 @@
+#!/usr/bin/env perl6
+# 
+#
+#       swing_to_the_left.raku
+#
+#         TASK #2 › Left Rotation
+#         Submitted by: Mohammad S Anwar
+#         You are given array @A containing positive numbers and @B containing
+#         one or more indices from the array @A.
+# 
+#         Write a script to left rotate @A so that the number at the first index
+#         of @B becomes the first element in the array. Similary, left rotate @A
+#         again so that the number at the second index of @B becomes the first
+#         element in the array.
+# 
+#         Example 1:
+#             Input:
+#                 @A = (10 20 30 40 50)
+#                 @B = (3 4)
+# 
+#         Explanation:
+#             a) We left rotate the 3rd index element (40) in the @A to make it 0th
+#             index member in the array.
+#                 [40 50 10 20 30]
+# 
+#             b) We left rotate the 4th index element (50) in the @A to make it 0th
+#             index member in the array.
+#                 [50 10 20 30 40]
+# 
+#         Output:
+#             [40 50 10 20 30]
+#             [50 10 20 30 40]
+# 
+#         Example 2:
+# 
+#         Input:
+#             @A = (7 4 2 6 3)
+#             @B = (1 3 4)
+# 
+#         Explanation:
+#             a) We left rotate the 1st index element (4) in the @A to make it
+#             0th index member in the array.
+#                 [4 2 6 3 7]
+# 
+#             b) We left rotate the 3rd index element (6) in the @A to make it
+#             0th index member in the array.
+#                 [6 3 7 4 2]
+# 
+#             c) We left rotate the 4th index element (3) in the @A to make it
+#             0th index member in the array.
+#                 [3 7 4 2 6]
+# 
+#         Output:
+#             [4 2 6 3 7]
+#             [6 3 7 5 2]
+#             [3 7 4 2 6]
+# 
+#         ----------------------------------------
+#
+#         method:
+#             I'm not sure "rotate" is exactly the right word for whats being
+#             asked for here, as rather what we are being asked to do is to
+#             produce the output as though the array had been rotated. The
+#             distinction is important as we need to retain the integrity of the
+#             original array and perform multiple transformations for output, as
+#             the transformations are not consecutivly applied in a churning
+#             fashion, but rather different applications to the starting
+#             sequence.
+# 
+#             The new sequences rearrange the elements such that the the tail of
+#             the array, starting at the indicated element, becomes the head,
+#             and the head, up to the break, becomes the tail. This can be done
+#             easily with array slices.
+# 
+#             As removing the head element and placing it on the end is the act
+#             of a left rotation, this is the same action moving a block of
+#             elements simultaniously rather than individual elements
+#             sequentially. In this sense it satisfies both the function and the
+#             spirit of the challenge.
+#
+#       2020 colin crain
+## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##
+
+
+
+unit sub MAIN (Str $arraystr = "7,4,2,6,3", Str $idxstr = "1,3,0,4") ;
+
+## in
+my @array = $arraystr.split(',');
+my @idxs  = $idxstr.split(',');
+my @output;
+
+## work
+for @idxs -> $idx {
+    $idx == 0 and do { @output.push: @array; next };
+    @output.push: @array[|($idx..@array.end), |^$idx]; 
+}
+
+## out
+say "array:       ", @array;
+say "index list:  ", @idxs;
+say "output:\n";
+.say for @output;