private static IEnumerable <List <Cave> > VisitAll(Cave cave, Dictionary <Cave, int> visited = null)
{
if (visited == null)
{
visited = new Dictionary <Cave, int>();
}
if (cave.Id == "end")
{
yield return(new List <Cave>()
{
cave
});
yield break;
}
if (!cave.CanVisit(visited))
{
yield break;
}
if (!cave.IsBigCave)
{
var count = visited.TryGetDef(cave, 0) + 1;
visited[cave] = count;
}
foreach (var neighbour in cave.Neighbours.Where(n => n.Id != "start"))
{
var dic = new Dictionary <Cave, int>(visited);
var paths = VisitAll(neighbour, dic);
foreach (var path in paths)
{
path.Add(cave);
yield return(path);
}
}
}