private NailNumber CheckSplit(ref bool split)
{
if (IsNumber)
{
if (_value > 9)
{
var node = new NailNumber(new NailNumber(_value / 2), new NailNumber((_value + 1) / 2));
node._left.SetPrevious(_previous);
_previous?.SetNext(node._left);
node._right.SetNext(_next);
_next?.SetPrevious(node._right);
split = true;
return(node);
}
}
else
{
_left = _left.CheckSplit(ref split);
if (split)
{
return(this);
}
_right = _right.CheckSplit(ref split);
}
return(this);
}
private NailNumber(NailNumber left, NailNumber right)
{
_left = left;
_right = right;
_left.SetNext(_right.Left());
_right.SetPrevious(_left.Right());
}
public static NailNumber Parse(CharEnumerator enumerator)
{
NailNumber result = null;
if (!enumerator.MoveNext())
{
return(null);
}
switch (enumerator.Current)
{
case '[':
var left = NailNumber.Parse(enumerator);
enumerator.MoveNext();
if (enumerator.Current != ',')
{
throw new InvalidOperationException("Failed to parse");
}
var right = NailNumber.Parse(enumerator);
enumerator.MoveNext();
if (enumerator.Current != ']')
{
throw new InvalidOperationException("Failed to parse");
}
result = new NailNumber(left, right);
break;
case >= '0' and <= '9':
result = new NailNumber(enumerator.Current - '0');
break;
}
return(result);
}
private NailNumber CheckExplode(ref bool explode, int depth = 0)
{
if (IsNumber)
{
return(this);
}
if (depth == 4)
{
// too deep
explode = true;
var node = new NailNumber(0);
if (_left._previous != null)
{
_left._previous._value += _left._value;
node.SetPrevious(_left._previous);
_left._previous.SetNext(node);
}
if (_right._next == null)
{
return(node);
}
_right._next._value += _right._value;
node.SetNext(_right._next);
_right._next.SetPrevious(node);
return(node);
}
_left = _left.CheckExplode(ref explode, depth + 1);
_right = _right.CheckExplode(ref explode, depth + 1);
return(this);
}
private void SetPrevious(NailNumber previous)
{
if (IsNumber)
{
_previous = previous;
}
else
{
Left().SetPrevious(previous);
}
}
private void SetNext(NailNumber next)
{
if (IsNumber)
{
_next = next;
}
else
{
Right().SetNext(next);
}
}
private NailNumber(NailNumber other)
{
if (other.IsNumber)
{
_value = other._value;
}
else
{
_left = new NailNumber(other._left);
_right = new NailNumber(other._right);
_left.SetNext(_right.Left());
_right.SetPrevious(_left.Right());
}
}
public NailNumber Add(NailNumber a)
{
var result = new NailNumber(new NailNumber(this), new NailNumber(a));
bool redo;
do
{
redo = false;
result.CheckExplode(ref redo);
if (!redo)
{
result.CheckSplit(ref redo);
}
} while (redo);
return(result);
}