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## Discussion of Problem 1054. Tower of Hanoi

Who solved problem1054,can you give me a example whose solution is "IMPOSSIBLE" or there is no such example?
Posted by Tests 16 Jun 2001 10:47
yeah, this case is impossible :">
Posted by Dinh Quang Hiep (mg9h@yahoo.com) 16 Jun 2001 11:53
2
2
1

Good luck !

QH@
Could you help me to find what's wrong,it my comprehesion right?
Posted by Roger 18 Jun 2001 20:12
const
maxN = 100;
pred : array[1..3]of longint = (3,1,2);
succ : array[1..3]of longint = (2,3,1);

var
now,tar : array[0..maxN]of longint;
ans,n : longint;

procedure Move(v,whi : longint);
var i,j,middle : longint;
begin
if whi=pred[now[v]] then middle:=succ[now[v]]
else middle:=pred[now[v]];
for i:=v-1 downto 1 do
if now[i]<>middle then Move(i,middle);
ans:=ans+1;
now[v]:=whi;
end;
var i : integer;
begin
for i:=1 to N do begin
now[i]:=1;
end;
for i:=n downto 1 do
if tar[i]<>now[i] then Move(i,tar[i]);
writeln(ans);
end.
Do you mean the answer of "2 2 1" is "no solution"?
Posted by Roger 19 Jun 2001 18:22
> 2
> 2
> 1
>
> Good luck !
>
> QH@

I think the answer is 3!
1
2              -->   2          -->       -->     1
3 empty empty        3 empty 1      3 2 1      3  2  empty

What wrong with the answer? Is my comprehesion wrong?
Re: Do you mean the answer of
Posted by Chen Xiaoke 1 Feb 2002 19:25
> > 2
> > 2
> > 1
> >
> > Good luck !
> >
> > QH@
>
> I think the answer is 3!
> 1
> 2              -->   2          -->       -->     1
> 3 empty empty        3 empty 1      3 2 1      3  2  empty
>
> What wrong with the answer? Is my comprehesion wrong?
>

your comprehesion is wrong. because you don't use the optimal
agoriythm
Re: Do you mean the answer of
Posted by Chen Xiaoke 1 Feb 2002 19:25
> > 2
> > 2
> > 1
> >
> > Good luck !
> >
> > QH@
>
> I think the answer is 3!
> 1
> 2              -->   2          -->       -->     1
> 3 empty empty        3 empty 1      3 2 1      3  2  empty
>
> What wrong with the answer? Is my comprehesion wrong?
>

your comprehesion is wrong. because you don't use the optimal
agoriythm