public string Generate(Board _board, GameUnit _unit, GameUnit _finishUnit)
{
var stringBuilder = new StringBuilder();
var words = MagicWordsStore.Words
.Concat(SpecialWords)
.ToArray();
var usedUnits = new HashSet<GameUnit>();
while (!_unit.Equals(_finishUnit))
{
if (TimeLimiter.NeedStop())
break;
foreach (var powerWord in words.OrderByDescending(x => x.Length))
{
if (TimeLimiter.NeedStop())
break;
var newlyUsedUnits = new HashSet<GameUnit>();
var currentUnit = _unit;
var fail = false;
for (var i = 0; i < powerWord.Length; ++i)
{
var command = powerWord[i];
newlyUsedUnits.Add(currentUnit);
var nextUnit = currentUnit.MakeStep(CommandConverter.Convert(command));
var locked = !_board.IsValid(nextUnit);
if (newlyUsedUnits.Contains(nextUnit) ||
usedUnits.Contains(nextUnit) ||
(locked && i < powerWord.Length - 1) ||
(locked && !nextUnit.Equals(_finishUnit)))
{
fail = true;
break;
}
if (!locked)
{
currentUnit = nextUnit;
}
}
var allUsedUnits = new HashSet<GameUnit>(usedUnits.Union(newlyUsedUnits));
if (!fail && ReachableStatesGetter.CanReach(_board, currentUnit, false, allUsedUnits, _finishUnit))
{
_unit = currentUnit;
usedUnits = allUsedUnits;
stringBuilder.Append(powerWord);
break;
}
}
}
foreach (var command in Enum.GetValues(typeof(Command)).Cast<Command>().Except(new[] { Command.Empty }))
{
if (!_board.IsValid(_unit.MakeStep(command)))
{
stringBuilder.Append(CommandConverter.CovertToAnyChar(command));
break;
}
}
return stringBuilder.ToString();
}
private static bool Dfs2(Board board, GameUnit unit, HashSet<GameUnit> newlyUsedUnits, HashSet<GameUnit> previouslyUsedUnits, HashSet<GameUnit> lockedUnits, GameUnit finishUnit)
{
if (unit.Equals(finishUnit))
return true;
newlyUsedUnits.Add(unit);
foreach (var command in Commands)
{
var nextUnit = unit.MakeStep(command);
if (!previouslyUsedUnits.Contains(nextUnit) && !newlyUsedUnits.Contains(nextUnit))
{
if (board.IsValid(nextUnit) && Dfs2(board, nextUnit, newlyUsedUnits, previouslyUsedUnits, lockedUnits, finishUnit))
{
return true;
}
else if (lockedUnits != null)
{
lockedUnits.Add(unit);
}
}
}
return false;
}