Merge pull request #1964 from waltman/branch-for-challenge-070

Branch for challenge 070

2 files changed, 111 insertions, 0 deletions

diff --git a/challenge-070/walt-mankowski/perl/ch-1.pl b/challenge-070/walt-mankowski/perl/ch-1.pl
new file mode 100644
index 0000000000..823119a0da
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+++ b/challenge-070/walt-mankowski/perl/ch-1.pl
@@ -0,0 +1,51 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use feature qw(:5.32);
+use experimental qw(signatures);
+
+# TASK #1 › Character Swapping
+# Submitted by: Mohammad S Anwar
+#
+# You are given a string $S of size $N.
+#
+# You are also given swap count $C and offset $O such that $C >= 1, $O
+# >= 1, $C <= $O and $C + $O <= $N.
+#
+# UPDATE: 2020-07-20 16:10:00 Pete Houston suggested to put additional
+# constraint i.e. $C <= $O. He presented the use case $S = 'abcd', $C
+# = 2, $O = 1.
+#
+# Write a script to perform character swapping like below:
+#
+# $S[ 1 % $N ] <=> $S[ (1 + $O) % $N ]
+# $S[ 2 % $N ] <=> $S[ (2 + $O) % $N ]
+# $S[ 3 % $N ] <=> $S[ (3 + $O) % $N ]
+# ...
+# ...
+# $S[ $C % $N ] <=> $S[ ($C + $O) % $N ]
+#
+# Example 1
+#
+# Input:
+#     $S = 'perlandraku'
+#     $C = 3
+#     $O = 4
+#
+# Character Swapping:
+#     swap 1: e <=> n = pnrlaedraku
+#     swap 2: r <=> d = pndlaerraku
+#     swap 3: l <=> r = pndraerlaku
+#
+# Output:
+#     pndraerlaku
+
+my ($s, $c, $o) = @ARGV;
+my $n = length($s);
+
+for my $i (1..$c) {
+    (substr($s, $i % $n,        1), substr($s, ($i + $o) % $n, 1)) =
+    (substr($s, ($i + $o) % $n, 1), substr($s, $i % $n,        1));
+}
+
+say $s;
diff --git a/challenge-070/walt-mankowski/perl/ch-2.pl b/challenge-070/walt-mankowski/perl/ch-2.pl
new file mode 100644
index 0000000000..c908d9b6b1
--- /dev/null
+++ b/challenge-070/walt-mankowski/perl/ch-2.pl
@@ -0,0 +1,60 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use feature qw(:5.32);
+use experimental qw(signatures);
+
+# TASK #2 › Gray Code Sequence
+# Submitted by: Mohammad S Anwar
+#
+# You are given an integer 2 <= $N <= 5.
+#
+# Write a script to generate $N-bit gray code sequence.
+#
+# 2-bit Gray Code Sequence
+#
+# [0, 1, 3, 2]
+#
+# To generate the 3-bit Gray code sequence from the 2-bit Gray code
+# sequence, follow the step below:
+#
+# 2-bit Gray Code sequence
+# [0, 1, 3, 2]
+#
+# Binary form of the sequence
+# a) S1 = [00, 01, 11, 10]
+#
+# Reverse of S1
+# b) S2 = [10, 11, 01, 00]
+#
+# Prefix all entries of S1 with '0'
+# c) S1 = [000, 001, 011, 010]
+#
+# Prefix all entries of S2 with '1'
+# d) S2 = [110, 111, 101, 100]
+#
+# Concatenate S1 and S2 gives 3-bit Gray Code sequence
+# e) [000, 001, 011, 010, 110, 111, 101, 100]
+#
+# 3-bit Gray Code sequence
+# [0, 1, 3, 2, 6, 7, 5, 4]
+#
+# Example
+#
+# Input: $N = 4
+#
+# Output: [0, 1, 3, 2, 6, 7, 5, 4, 12, 13, 15, 14, 10, 11, 9, 8]
+
+my $n = $ARGV[0];
+my @S = (0, 1, 3, 2);
+
+for my $i (3..$n) {
+    @S = gray_code($i, @S);
+}
+
+say "@S";
+
+sub gray_code($n, @S) {
+    my @S2 = map { "1$_" } reverse map { scalar sprintf "%.*b", $n-1, $_ } @S;
+    return @S, map { eval "0b$_" } @S2;
+}