public void SensibleEnqueue(Jug3State candidate)
{
foreach (Jug3State state in _visited)
{
if (state.Equals(candidate))
{
return;
}
}
foreach (Jug3State state in _queue)
{
if (state.Equals(candidate))
{
return;
}
}
_queue.Enqueue(candidate);
}
int?Generate()
{
Jug3State head = _queue.Dequeue();
_visited.Add(head);
// for all states there are 2 actions
// empty a
Jug3State emptyA = StateClone(head);
emptyA.JugA.Empty();
SensibleEnqueue(emptyA);
// fill a
Jug3State fillA = StateClone(head);
fillA.JugA.Fill();
if (_target == fillA.JugA.Current)
{
return(fillA.Moves);
}
SensibleEnqueue(fillA);
// if there are at least two jugs, there are 4 new actions
if (_numberOfJugs >= 2)
{
// empty b
Jug3State emptyB = StateClone(head);
emptyB.JugB.Empty();
SensibleEnqueue(emptyB);
// fill b
Jug3State fillB = StateClone(head);
fillB.JugB.Fill();
if (_target == fillB.JugA.Current)
{
return(fillB.Moves);
}
SensibleEnqueue(fillB);
// transfer a->b
Jug3State aToB = StateClone(head);
aToB.JugA.TransferTo(aToB.JugB);
if (_target == aToB.JugA.Current || _target == aToB.JugB.Current)
{
return(aToB.Moves);
}
SensibleEnqueue(aToB);
// transfer b-> a
Jug3State bToA = StateClone(head);
bToA.JugB.TransferTo(bToA.JugA);
if (_target == bToA.JugA.Current || _target == bToA.JugB.Current)
{
return(bToA.Moves);
}
SensibleEnqueue(bToA);
}
// inductively
// if there are at least 3 jugs
if (_numberOfJugs >= 3)
{
// empty c
Jug3State emptyC = StateClone(head);
emptyC.JugC.Empty();
SensibleEnqueue(emptyC);
// fill C
Jug3State fillC = StateClone(head);
fillC.JugC.Fill();
if (_target == fillC.JugA.Current)
{
return(fillC.Moves);
}
SensibleEnqueue(fillC);
// transfer a->c
Jug3State aToC = StateClone(head);
aToC.JugA.TransferTo(aToC.JugC);
if (_target == aToC.JugA.Current || _target == aToC.JugC.Current)
{
return(aToC.Moves);
}
SensibleEnqueue(aToC);
// transfer c-> a
Jug3State cToA = StateClone(head);
cToA.JugC.TransferTo(cToA.JugA);
if (_target == cToA.JugA.Current || _target == cToA.JugC.Current)
{
return(cToA.Moves);
}
SensibleEnqueue(cToA);
// transfer B->c
Jug3State bToC = StateClone(head);
bToC.JugB.TransferTo(bToC.JugC);
if (_target == bToC.JugB.Current || _target == bToC.JugC.Current)
{
return(bToC.Moves);
}
SensibleEnqueue(bToC);
// transfer c-> B
Jug3State cToB = StateClone(head);
cToB.JugC.TransferTo(cToB.JugB);
if (_target == cToB.JugB.Current || _target == cToB.JugC.Current)
{
return(cToB.Moves);
}
SensibleEnqueue(cToB);
}
return(null);
}
static Jug3State StateClone(Jug3State head)
{
return(new Jug3State(head.JugA.Clone(), head.JugB.Clone(), head.JugC.Clone(), head.Moves + 1));
}
