discrete and cominatorial math chapter 1_1
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#/usr/bin/env perl6
use v6;
"The rule of sum".say;
say q:to/EOF/;
Ex:
Frank wants to go to Taipei.
He can choose from bus services or train services to head from home to Hsinchu .
From there, he can choose from 2 bus services or 3 train services to head to Taipei.
{ bus: Kuo-Kuang Greyhound-Line , train: Amtrak Krtco Metro-Taipei }
How many ways are there for Hsinchu to get to Taipei?
EOF
my Sub @byBus = gather for < Kuo-Kuang Greyhound-Line > -> $name {
take &trafficMethod( :way( $name ) )
}
my Sub @byTrain = gather for < Amtrak Krtco Metro-Taipei > -> $name {
take &trafficMethod( :way( $name ) )
}
say "We have { &count( @byBus, @byTrain) :rule("sum")} way to reach it\n";
"The rule of product".say;
say q:to/EOF/;
EX:
How many situation of "rock paper scissors" game for two player
EOF
my @player := <rock paper scissors> ;
say "We have { &count( @player, @player ) } situation";
sub trafficMethod ( Str :$way!, Str :$from? = 'Hsinchu', Str :$to? = 'Taipei' --> Sub ) {
return sub { "form $from to $to by $way".say }
}
sub count( List $a where $a.elems > 0, List $b where $b.elems > 0, :$rule? = 'product' --> Int ) {
given $rule {
when 'product' { $a.elems * $b.elems }
when 'sum' { $a.elems + $b.elems }
default { die "I don't know the option of $rule mean !\n" }
}
}
Raku
INFO