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Perl 6Advent Calendar 2017

Day 12

Advent of Code day7をPerl 6で

Last updated at Posted at 2017-12-14

こんにちは、12日目は投稿がなかったので
私のAdvent of Code day7の回答を貼っておきます。

use v6;                                                                       
                                                                              
grammar Grammar {                                                             
    token TOP {                                                               
        [                                                                     
            <name> <.ws> '('<weight>')' [ <.ws> '->' <.ws> <namelist> ]?      
        ]                                                                     
    }                                                                         
    token namelist {                                                          
        <name>+ % ', '                                                        
    }                                                                         
    token name {                                                              
        \w+                                                                   
    }                                                                         
    token weight {                                                            
        \d+                                                                   
    }                                                                         
}                                                                             
                                                                              
                                                                              
my %is-root;                                                                  
for $*IN.lines -> $line {                                                     
    my $m = Grammar.parse($line);                                             
    %is-root{~$m<name>} = True unless %is-root{~$m<name>}:exists;             
                                                                              
    if $m<namelist>:exists {                                                  
        for $m<namelist><name> {                                              
            %is-root{~$_} = False;                                            
        }                                                                     
    }                                                                         
}                                                                             
                                                                              
do for %is-root -> (:key($name), :value($)) {                                 
    $name if %is-root{$name};                                                 
}.head.say;                                                                   
  
  • ポイント
    • Grammar使うときれいにかけます。
    • .oO( weightとは何だったんでしょうか??? )

以上12日目の投稿でした。

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