Simon's solution to challenge 220

6 files changed, 131 insertions, 1 deletions

diff --git a/challenge-220/sgreen/README.md b/challenge-220/sgreen/README.md
index b0c3afab92..4166d8271b 100644
--- a/challenge-220/sgreen/README.md
+++ b/challenge-220/sgreen/README.md
@@ -1,3 +1,3 @@
 # The Weekly Challenge 219
 
-Blog: [The cheapest way to the square](https://dev.to/simongreennet/the-cheapest-way-to-the-square-1mhb)
+Blog: [Common squares](https://dev.to/simongreennet/common-squares-31do)
diff --git a/challenge-220/sgreen/blog.txt b/challenge-220/sgreen/blog.txt
new file mode 100644
index 0000000000..573b53471f
--- /dev/null
+++ b/challenge-220/sgreen/blog.txt
@@ -0,0 +1 @@
+https://dev.to/simongreennet/common-squares-31do
\ No newline at end of file
diff --git a/challenge-220/sgreen/perl/ch-1.pl b/challenge-220/sgreen/perl/ch-1.pl
new file mode 100755
index 0000000000..eb4113d626
--- /dev/null
+++ b/challenge-220/sgreen/perl/ch-1.pl
@@ -0,0 +1,40 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use feature 'say';
+use experimental 'signatures';
+
+use List::Util qw(all);
+
+sub word_to_hash ($word) {
+    my %hash = ();
+    foreach my $letter ( split //, lc $word ) {
+        $hash{$letter} = 1;
+    }
+    return \%hash;
+}
+
+sub main (@words) {
+    # Turns the words into a list of hashes, and take off the first word
+    my @set_list   = ( map { word_to_hash($_) } @words );
+    my $first_word = shift(@set_list);
+    my @letters    = ();
+
+    # Go through each letter in the first word
+    foreach my $letter ( sort keys(%$first_word) ) {
+        # And checks it is used in all other words
+        if (    'a' le $letter
+            and $letter le 'z'
+            and all { exists $_->{$letter} } @set_list )
+        {
+            # It is! Add it to the letters list
+            push @letters, $letter;
+        }
+    }
+
+    say join( ', ', @letters );
+
+}
+
+main(@ARGV);
diff --git a/challenge-220/sgreen/perl/ch-2.pl b/challenge-220/sgreen/perl/ch-2.pl
new file mode 100755
index 0000000000..b0af768b95
--- /dev/null
+++ b/challenge-220/sgreen/perl/ch-2.pl
@@ -0,0 +1,36 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use feature 'say';
+use experimental 'signatures';
+
+use Algorithm::Combinatorics qw(permutations);
+use List::Util               qw(any);
+
+sub main (@ints) {
+    my @solution = ();
+
+    my $iter = permutations( \@ints );
+  P: while ( my $p = $iter->next ) {
+        # Have we seen this solution before
+        my $string = '(' . join( ', ', @$p ) . ')';
+        next if any { $_ eq $string } @solution;
+
+        # Is each pair a square of an integer
+        foreach my $i ( 1 .. $#ints ) {
+            my $sqrt = sqrt( $p->[ $i - 1 ] + $p->[$i] );
+            if ( $sqrt != int($sqrt) ) {
+                next P;
+            }
+        }
+
+        # It is. Add a formatted version of these items to the solution array.
+        push @solution, $string;
+    }
+
+    say join( ', ', @solution );
+
+}
+
+main(@ARGV);
diff --git a/challenge-220/sgreen/python/ch-1.py b/challenge-220/sgreen/python/ch-1.py
new file mode 100755
index 0000000000..60df7c4cff
--- /dev/null
+++ b/challenge-220/sgreen/python/ch-1.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+import string
+import sys
+
+
+def main(words):
+    # Turns the words into a set list, and take off the first word
+    set_list = [set(w.lower()) for w in words]
+    first_word = set_list.pop(0)
+    letters = []
+
+    # Go through each letter in the first word
+    for letter in sorted(first_word):
+        # And checks it is used in all other words
+        if 'a' < letter < 'z' and all(letter in x for x in set_list):
+            # It is! Add it to the letters list
+            letters.append(letter)
+
+    print(*letters, sep=', ')
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])
diff --git a/challenge-220/sgreen/python/ch-2.py b/challenge-220/sgreen/python/ch-2.py
new file mode 100755
index 0000000000..d483abe7cf
--- /dev/null
+++ b/challenge-220/sgreen/python/ch-2.py
@@ -0,0 +1,29 @@
+#!/usr/bin/env python
+
+import math
+import sys
+from itertools import permutations
+
+
+def main(ints):
+    solution = []
+    for p in permutations(ints):
+        # Have we seen this solution before
+        if p in solution:
+            continue
+
+        # Is each pair a square of an integer
+        for i in range(1, len(ints)):
+            sqrt = math.sqrt(p[i-1] + p[i])
+            if sqrt != int(sqrt):
+                break
+        else:
+            # It is. Add it the solution if we haven't seen it before
+            solution.append(p)
+
+    print(*solution, sep=', ')
+
+
+if __name__ == '__main__':
+    array = [int(n) for n in sys.argv[1:]]
+    main(array)