The weekly challenge 364 - Task 2: Goal Parser

  1 #!/usr/bin/env perl
  2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-364/#TASK2
  3 #
  4 # Task 2: Goal Parser
  5 # ===================
  6 #
  7 # You are given a string, $str.
  8 #
  9 # Write a script to interpret the given string using Goal Parser.
 10 #
 11 ##     The Goal Parser interprets “G” as the string “G”, “()” as the string
 12 ##     “o”, and “(al)” as the string “al”. The interpreted strings are then
 13 ##     concatenated in the original order.
 14 #
 15 ## Example 1
 16 ##
 17 ## Input: $str = "G()(al)"
 18 ## Output: "Goal"
 19 ##
 20 ## G    -> "G"
 21 ## ()   -> "o"
 22 ## (al) -> "al"
 23 #
 24 ## Example 2
 25 ##
 26 ## Input: $str = "G()()()()(al)"
 27 ## Output: "Gooooal"
 28 ##
 29 ## G       -> "G"
 30 ## four () -> "oooo"
 31 ## (al)    -> "al"
 32 #
 33 ## Example 3
 34 ##
 35 ## Input: $str = "(al)G(al)()()"
 36 ## Output: "alGaloo"
 37 ##
 38 ## (al) -> "al"
 39 ## G    -> "G"
 40 ## (al) -> "al"
 41 ## ()   -> "o"
 42 ## ()   -> "o"
 43 #
 44 ## Example 4
 45 ##
 46 ## Input: $str = "()G()G"
 47 ## Output: "oGoG"
 48 ##
 49 ## () -> "o"
 50 ## G  -> "G"
 51 ## () -> "o"
 52 ## G  -> "G"
 53 #
 54 ## Example 5
 55 ##
 56 ## Input: $str = "(al)(al)G()()"
 57 ## Output: "alalGoo"
 58 ##
 59 ## (al) -> "al"
 60 ## (al) -> "al"
 61 ## G    -> "G"
 62 ## ()   -> "o"
 63 ## ()   -> "o"
 64 #
 65 ############################################################
 66 ##
 67 ## discussion
 68 ##
 69 ############################################################
 70 #
 71 # As long as there are still characters in $str, we remove either
 72 # a starting "G", "()" or "(al)", and add a "G", "o" or "al" to
 73 # the result.
 74 
 75 use v5.36;
 76 
 77 goal_parser("G()(al)");
 78 goal_parser("G()()()()(al)");
 79 goal_parser("(al)G(al)()()");
 80 goal_parser("()G()G");
 81 goal_parser("(al)(al)G()()");
 82 
 83 sub goal_parser($str) {
 84     say "Input: \"$str\"";
 85     my $result = "";
 86     while(length($str)) {
 87         if($str =~ m/^G/ ) {
 88             $result .= "G";
 89             $str =~ s/^.//;
 90         } elsif ($str =~ m/^\(\)/) {
 91             $result .= "o";
 92             $str =~ s/^..//;
 93         } elsif ($str =~ m/^\(al\)/) {
 94             $result .= "al";
 95             $str =~ s/^....//;
 96         } else {
 97             die "Unrecognized pattern in $str";
 98         }
 99     }
100     say "Output: \"$result\"";
101 }