Add solutions for challenge 207

Signed-off-by: Thomas Köhler <jean-luc@picard.franken.de>

4 files changed, 143 insertions, 0 deletions

diff --git a/challenge-207/jeanluc2020/blog-1.txt b/challenge-207/jeanluc2020/blog-1.txt
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+http://gott-gehabt.de/800_wer_wir_sind/thomas/Homepage/Computer/perl/theweeklychallenge-207-1.html
diff --git a/challenge-207/jeanluc2020/blog-2.txt b/challenge-207/jeanluc2020/blog-2.txt
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+http://gott-gehabt.de/800_wer_wir_sind/thomas/Homepage/Computer/perl/theweeklychallenge-207-2.html
diff --git a/challenge-207/jeanluc2020/perl/ch-1.pl b/challenge-207/jeanluc2020/perl/ch-1.pl
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+#!/usr/bin/perl
+# https://theweeklychallenge.org/blog/perl-weekly-challenge-207/#TASK1
+#
+# Task 1: Keyboard Word
+# =====================
+#
+# You are given an array of words.
+#
+# Write a script to print all the words in the given array that can be types using alphabet on only one row of the keyboard.
+#
+# Let us assume the keys are arranged as below:
+#
+# Row 1: qwertyuiop
+# Row 2: asdfghjkl
+# Row 3: zxcvbnm
+#
+## Example 1
+##
+## Input: @words = ("Hello","Alaska","Dad","Peace")
+## Output: ("Alaska","Dad")
+#
+## Example 2
+##
+## Input: @array = ("OMG","Bye")
+## Output: ()
+#
+############################################################
+##
+## discussion
+##
+############################################################
+#
+# Basically, for all input words, we create the same word in
+# lowercase and for each keyboard row, we check whether we can
+# build this word with this row and add it to the output if we
+# can
+
+use strict;
+use warnings;
+use feature 'say';
+
+keyboard_word("Hello","Alaska","Dad","Peace");
+keyboard_word("OMG","Bye");
+
+sub keyboard_word {
+   my @words = @_;
+   my @output = ();
+   foreach my $word (@words) {
+      # if the lowercase "lc()" version of $word is a keyboard
+      # word, we can push the word onto the output
+      push @output, $word if is_keyboard_word(lc($word));
+   }
+   say "Input: (" . join(",", @words) . ")";
+   say "Output: (" . join(",", @output) . ")";
+}
+
+sub is_keyboard_word {
+   my $word = shift;
+   my @rows = ( "qwertyuiop", "asdfghjkl", "zxcvbnm");
+   my @chars = split //, $word;
+   foreach my $row (@rows) {
+      # if $found_all is still 1 after all characters have been
+      # found in the current row, we found a keyboard word
+      my $found_all = 1;
+      foreach my $char (@chars) {
+         if($row !~ m/$char/) {
+            # we found a character that is not in this row
+            $found_all = 0;
+         }
+      }
+      return 1 if $found_all;
+   }
+   # we haven't found all characters in the same row for all rows
+   return 0;
+}
diff --git a/challenge-207/jeanluc2020/perl/ch-2.pl b/challenge-207/jeanluc2020/perl/ch-2.pl
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+#!/usr/bin/perl
+# https://theweeklychallenge.org/blog/perl-weekly-challenge-207/#TASK2
+#
+# Task 2: H-Index
+# ===============
+#
+# You are given an array of integers containing citations a researcher has
+# received for each paper.
+#
+# Write a script to compute the researcher’s H-Index. For more information
+# please checkout the wikipedia page.
+#
+###   The H-Index is the largest number h such that h articles have at least h
+###   citations each. For example, if an author has five publications, with 9,
+###   7, 6, 2, and 1 citations (ordered from greatest to least), then the
+###   author’s h-index is 3, because the author has three publications with 3
+###   or more citations. However, the author does not have four publications
+###   with 4 or more citations.
+#
+#
+## Example 1
+##
+## Input: @citations = (10,8,5,4,3)
+## Output: 4
+##
+## Because the 4th publication has 4 citations and the 5th has only 3.
+#
+## Example 2
+##
+## Input: @citations = (25,8,5,3,3)
+## Output: 3
+##
+## The H-Index is 3 because the fourth paper has only 3 citations.
+#
+############################################################
+##
+## discussion
+##
+############################################################
+#
+# Basically you count from 1 to the number of publications and
+# check the number of citations for each. If the number of
+# citations drops below the current index, you found the H-Index
+
+use strict;
+use warnings;
+use feature 'say';
+
+h_index(10,8,5,4,3);
+h_index(25,8,5,3,3);
+h_index(7,6,5,6,7,5,5);
+h_index(7,6,5,6);
+
+sub h_index {
+   my @citations = sort {$b <=> $a} @_;
+   say "Input: (" . join(",", @citations) . ")";
+   my $h = 0;
+   foreach my $c (@citations) {
+      $h++;
+      if($h > $c) {
+         $h--;
+         last;
+      }
+   }
+   say "Output $h";
+}