30 lines
752 B
Plaintext
30 lines
752 B
Plaintext
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###
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### check_move
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###
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## Chapter 1 section 3
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@position = (' ', ('A') x 3); # Disks are all initially on peg A
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sub check_move {
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my $i;
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my ($disk, $start, $end) = @_;
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if ($disk < 1 || $disk > $#position) {
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die "Bad disk number $disk. Should be 1..$#position.\n";
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}
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unless ($position[$disk] eq $start) {
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die "Tried to move disk $disk from $start, but it is on peg $position[$disk].\n";
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}
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for $i (1 .. $disk-1) {
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if ($position[$i] eq $start) {
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die "Can't move disk $disk from $start because $i is on top of it.\n";
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} elsif ($position[$i] eq $end) {
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die "Can't move disk $disk to $end because $i is already there.\n";
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}
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}
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print "Moving disk $disk from $start to $end.\n";
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$position[$disk] = $end;
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}
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