public object Solve()
{
var dependencies = new DependencyMatrix(cars);
var lanes = new LaneList(cars);
var initialListIsOk = lanes.TryUpdate(dependencies);
Debug.Assert(initialListIsOk);
foreach (var e in Events.Enumerate(cars))
{
Debug.Assert(e.Time >= 0);
if (e.Type == EventType.StartOverlapping)
{
if (!dependencies.TryPutCarsOnOppositeLanes(e.Car1, e.Car2))
return e.Time;
}
if (e.Type == EventType.StopOverlapping)
{
dependencies.RemoveCarsOnOppositeLanes(e.Car1, e.Car2);
}
if (!lanes.TryUpdate(dependencies))
return e.Time;
}
return "Possible";
}
public bool TryUpdate(DependencyMatrix dependencies)
{
for (int car1 = 0; car1 < lanes.Length; car1++)
{
if (dependencies.IsIndependent(car1))
{
lanes[car1] = Lane.Undeterminated;
continue;
}
foreach (var car2 in dependencies.GetCarsOnSameLane(car1))
{
if (lanes[car2] == Lane.Undeterminated) continue;
if (lanes[car1] == Lane.Undeterminated)
lanes[car1] = lanes[car2];
else if (lanes[car1] != lanes[car2])
return false;
}
foreach (var car2 in dependencies.GetCarsOnOppositeLane(car1))
{
if (lanes[car2] == Lane.Undeterminated) continue;
if (lanes[car1] == Lane.Undeterminated)
lanes[car1] = lanes[car2].Opposite();
else if (lanes[car1] == lanes[car2])
return false;
}
}
return true;
}
public object Solve()
{
var dependencies = new DependencyMatrix(cars);
var lanes = new LaneList(cars);
var initialListIsOk = lanes.TryUpdate(dependencies);
Debug.Assert(initialListIsOk);
foreach (var e in Events.Enumerate(cars))
{
Debug.Assert(e.Time >= 0);
if (e.Type == EventType.StartOverlapping)
{
if (!dependencies.TryPutCarsOnOppositeLanes(e.Car1, e.Car2))
{
return(e.Time);
}
}
if (e.Type == EventType.StopOverlapping)
{
dependencies.RemoveCarsOnOppositeLanes(e.Car1, e.Car2);
}
if (!lanes.TryUpdate(dependencies))
{
return(e.Time);
}
}
return("Possible");
}
void GetInitialCarDependencies(DependencyMatrix matrix)
{
// make dependencies
for (int i = 0; i < cars.Length; i++)
{
for (int j = i + 1; j < cars.Length; j++)
{
if (AreOverlapping(cars[i].InitialPosition, cars[j].InitialPosition))
{
var ok = matrix.TryAddOvertake(i, j);
Debug.Assert(ok);
}
}
}
}
public bool TryUpdate(DependencyMatrix dependencies)
{
for (int car1 = 0; car1 < lanes.Length; car1++)
{
if (dependencies.IsIndependent(car1))
{
lanes[car1] = Lane.Undeterminated;
continue;
}
foreach (var car2 in dependencies.GetCarsOnSameLane(car1))
{
if (lanes[car2] == Lane.Undeterminated)
{
continue;
}
if (lanes[car1] == Lane.Undeterminated)
{
lanes[car1] = lanes[car2];
}
else if (lanes[car1] != lanes[car2])
{
return(false);
}
}
foreach (var car2 in dependencies.GetCarsOnOppositeLane(car1))
{
if (lanes[car2] == Lane.Undeterminated)
{
continue;
}
if (lanes[car1] == Lane.Undeterminated)
{
lanes[car1] = lanes[car2].Opposite();
}
else if (lanes[car1] == lanes[car2])
{
return(false);
}
}
}
return(true);
}
public object Solve()
{
var matrix = new DependencyMatrix(cars.Length);
var lanes = cars.Select(x => x.InitialLane).ToArray();
GetInitialCarDependencies(matrix);
var ok = TryUpdateLaneList(matrix, lanes);
Debug.Assert(ok);
var events = EnumerateEvents().OrderBy(x => x.Type).OrderBy(x => x.Time);
foreach (var e in events)
{
#if TRACE
Log("Dependencies:");
Log("{0}", matrix);
Log("Lanes:");
for (var car = 0; car < lanes.Length; car++)
{
Log("{0} = {1}", car, lanes[car]);
}
Log("At {3}, event {0} with {1} and {2}", e.Type, e.Car1, e.Car2, e.Time);
#endif
if (e.Type == EventType.Enter)
{
if (!matrix.TryAddOvertake(e.Car1, e.Car2))
{
return(e.Time);
}
}
else
{
matrix.RemoveOvertake(e.Car1, e.Car2);
}
if (!TryUpdateLaneList(matrix, lanes))
{
return(e.Time);
}
}
return("Possible");
}
public object Solve()
{
var matrix = new DependencyMatrix(cars.Length);
var lanes = cars.Select(x => x.InitialLane).ToArray();
GetInitialCarDependencies(matrix);
var ok = TryUpdateLaneList(matrix, lanes);
Debug.Assert(ok);
var events = EnumerateEvents().OrderBy(x => x.Type).OrderBy(x => x.Time);
foreach (var e in events)
{
#if TRACE
Log("Dependencies:");
Log("{0}", matrix);
Log("Lanes:");
for (var car = 0; car < lanes.Length; car++)
Log("{0} = {1}", car, lanes[car]);
Log("At {3}, event {0} with {1} and {2}", e.Type, e.Car1, e.Car2, e.Time);
#endif
if (e.Type == EventType.Enter)
{
if (!matrix.TryAddOvertake(e.Car1, e.Car2))
return e.Time;
}
else
{
matrix.RemoveOvertake(e.Car1, e.Car2);
}
if (!TryUpdateLaneList(matrix, lanes))
return e.Time;
}
return "Possible";
}
void GetInitialCarDependencies(DependencyMatrix matrix)
{
// make dependencies
for (int i = 0; i < cars.Length; i++)
{
for (int j = i+1; j < cars.Length; j++)
{
if (AreOverlapping(cars[i].InitialPosition, cars[j].InitialPosition))
{
var ok = matrix.TryAddOvertake(i, j);
Debug.Assert(ok);
}
}
}
}