public PathFinder()
{
bfs = new BFS();
dfs = new DFS();
dj = new Dijkstra();
aStart = new AStart(AStartHeuristic.Euclid);
}
// 参考 启发性搜索 A*算法
// f(n) = g(n) + h(n)
// f(n) 为最小代价
// g(n) 为初始状态到当前状态的代价
// h(n) 为当前状态到目标状态的代价
public static int OpenLock(string[] deadends, string target)
{
if (target == "0000")
{
return(0);
}
HashSet <string> dead = deadends.ToHashSet();
if (dead.Contains("0000"))
{
return(-1);
}
Heap <AStart> heap = new Heap <AStart>(false);
heap.Insert(new AStart("0000", target, 0));
HashSet <string> seen = new HashSet <string>();
seen.Add("0000");
while (!heap.Empty)
{
AStart node = heap.Pop();
foreach (var nextStatus in Get(node.Status))
{
if (!seen.Contains(nextStatus) && !dead.Contains(nextStatus))
{
if (nextStatus == target)
{
return(node.G + 1);
}
heap.Insert(new AStart(nextStatus, target, node.G + 1));
seen.Add(nextStatus);
}
}
}
return(-1);
}
