Towers of Hanoi: Difference between revisions

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In this task, the goal is to solve the Towers of Hanoi problem with recursivity.

Ada

with Ada.Text_Io; use Ada.Text_Io;

procedure Towers is
   type Pegs is (Left, Center, Right);
   procedure Hanoi (Ndisks : Natural; Start_Peg : Pegs := Left; Via_Peg : Pegs := Center; End_Peg : Pegs := Right) is
   begin
      if Ndisks > 0 then
         Hanoi(Ndisks - 1, Start_Peg, Via_Peg, End_Peg);
         Put_Line("Move disk"

Revision as of 06:17, 2 September 2007 view source rosettacode>Waldorf Undo revision 8085 by Special:Contributions/On5M1p (User talk:On5M1p) ← Older edit		Revision as of 05:49, 4 September 2007 view source rosettacode>On5M1p mNo edit summary Newer edit →
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the goal is to solve the Towers of Hanoi problem with recursivity. Line 13: if Ndisks > 0 then Hanoi(Ndisks - 1, Start_Peg, Via_Peg, End_Peg); Put_Line("Move disk" ~~& Natural'Image(Ndisks) & " from " & Pegs'Image(Start_Peg) & " to " &~~ ~~Pegs'Image(End_Peg));~~ ~~Hanoi(Ndisks - 1, Via_Peg, End_Peg, Start_Peg);~~ ~~end if;~~ ~~end Hanoi;~~ ~~begin~~ ~~Hanoi(4);~~ ~~end Towers;~~ ~~==[[AppleScript]]==~~ ~~[[Category:AppleScript]]~~ ~~global moves --this is so the handler 'hanoi' can see the 'moves' variable~~ ~~set moves to ""~~ ~~hanoi(4, "peg A", "peg C", "peg B")~~ ~~on hanoi(ndisks, fromPeg, toPeg, withPeg)~~ ~~if ndisks is greater than 0 then~~ ~~hanoi(ndisks - 1, fromPeg, withPeg, toPeg)~~ ~~set moves to moves & "Move disk " & ndisks & " from " & fromPeg & " to " & toPeg & return~~ ~~hanoi(ndisks - 1, withPeg, toPeg, fromPeg)~~ ~~end if~~ ~~return moves~~ ~~end hanoi~~ ~~==[[C plus plus\|C++]]==~~ ~~[[Category:C plus plus]]~~ ~~'''Compiler:''' [[GCC]]~~ ~~void move(int n, int from, int to, int via) {~~ ~~if (n == 1) {~~ ~~std::cout << "Move disk from pole " << from << " to pole " << to << std::endl;~~ ~~} else {~~ ~~move(n - 1, from, via, to);~~ ~~move(1, from, to, via);~~ ~~move(n - 1, via, to, from);~~ } } ~~==[[E]]==~~ ~~[[Category:E]]~~ ~~def move(out, n, fromPeg, toPeg, viaPeg) {~~ ~~if (n.aboveZero()) {~~ ~~move(out, n.previous(), fromPeg, viaPeg, toPeg)~~ ~~out.println(`Move disk $n from $fromPeg to $toPeg.`)~~ ~~move(out, n.previous(), viaPeg, toPeg, fromPeg)~~ } } ~~move(stdout, 4, def left {}, def right {}, def middle {})~~ ~~==[[Forth]]==~~ ~~[[Category:Forth]]~~ ~~With locals:~~ ~~CREATE peg1 ," left "~~ ~~CREATE peg2 ," middle "~~ ~~CREATE peg3 ," right "~~ ~~: .$ COUNT TYPE ;~~ ~~: MOVE-DISK~~ ~~LOCALS\| via to from n \|~~ ~~n 1 =~~ ~~IF CR ." Move disk from " from .$ ." to " to .$~~ ~~ELSE n 1- from via to RECURSE~~ ~~1 from to via RECURSE~~ ~~n 1- via to from RECURSE~~ ~~THEN ;~~ ~~Without locals, executable pegs:~~ ~~: left ." left" ;~~ ~~: right ." right" ;~~ ~~: middle ." middle" ;~~ ~~: print ( t f -- )~~ ~~CR ." Move disk from " execute ." to " execute ;~~ ~~: move-disk ( v t f n -- v t f )~~ ~~dup 1 = if drop 2dup print exit then~~ ~~1- >R~~ ~~rot swap R@ ( t v f n-1 ) recurse~~ ~~rot swap 2dup print~~ ~~swap rot R> ( f t v n-1 ) recurse~~ ~~swap rot ;~~ ~~: hanoi ( n -- )~~ ~~1 max >R ['] right ['] middle ['] left R> move-disk drop drop drop ;~~ ~~==[[Java]]==~~ ~~[[Category:Java]]~~ ~~public void move(int n, int from, int to, int via) {~~ ~~if (n == 1) {~~ ~~System.out.println("Move disk from pole " + from + " to pole " + to);~~ ~~} else {~~ ~~move(n - 1, from, via, to);~~ ~~move(1, from, to, via);~~ ~~move(n - 1, via, to, from);~~ } } ~~==[[Perl]]==~~ ~~[[Category:Perl]]~~ ~~sub move {~~ ~~my $n = shift;~~ ~~my $from = shift;~~ ~~my $to = shift;~~ ~~my $via = shift;~~ ~~if ($n == 1) {~~ ~~print "Move disk from pole $from to pole $to.\n";~~ ~~} else {~~ ~~move($n - 1, $from, $via, $to);~~ ~~move(1, $from, $to, $via);~~ ~~move($n - 1, $via, $to, $from);~~ }; }; ~~==[[Pop11]]==~~ ~~[[Category:Pop11]]~~ ~~define hanoi(n, src, dst, via);~~ ~~if n > 0 then~~ ~~hanoi(n - 1, src, via, dst);~~ ~~printf('Move disk ' >< n >< ' from ' >< src >< ' to ' >< dst >< '.\n');~~ ~~hanoi(n - 1, via, dst, src);~~ ~~endif;~~ ~~enddefine;~~ ~~hanoi(4, "left", "middle", "right");~~ ~~==[[Python]]==~~ ~~[[Category:Python]]~~ ~~<pre>~~ ~~def hanoi(ndisks, startPeg=1, endPeg=3):~~ ~~if ndisks:~~ ~~hanoi(ndisks-1, startPeg, 6-startPeg-endPeg)~~ ~~print "Move disk %d from peg %d to peg %d" % (ndisks, startPeg, endPeg)~~ ~~hanoi(ndisks-1, 6-startPeg-endPeg, endPeg)~~ ~~hanoi(ndisks=4)~~ ~~</pre>~~ ~~==[[Seed7]]==~~ ~~[[Category:Seed7]]~~ ~~const proc: hanoi (in integer: disk, in string: source, in string: dest, in string: via) is func~~ ~~begin~~ ~~if disk > 0 then~~ ~~hanoi(pred(disk), source, via, dest);~~ ~~writeln("Move disk " <& disk <& " from " <& source <& " to " <& dest);~~ ~~hanoi(pred(disk), via, dest, source);~~ ~~end if;~~ ~~end func;~~ ~~==[[Toka]]==~~ ~~[[Category:Toka]]~~ ~~value\| sa sb sc n \|~~ ~~[ to sc to sb to sa to n ] is vars!~~ ~~[ ( num from to via -- )~~ ~~vars!~~ ~~n 0 <>~~ [ ~~n sa sb sc~~ ~~n 1- sa sc sb recurse~~ ~~vars!~~ ~~." Move a ring from " sa . ." to " sb . cr~~ ~~n 1- sc sb sa recurse~~ ~~] ifTrue~~ ~~] is hanoi~~