/// <summary>
/// 获得最短路径。
/// </summary>
/// <param name="start">起始状态。</param>
/// <param name="goal">终止状态。</param>
/// <returns></returns>
public T[] GetPath(T start, T goal)
{
Dictionary <T, T> comeFrom = new Dictionary <T, T>(this.equalityComparer);
Dictionary <T, int> gScore = new Dictionary <T, int>(this.equalityComparer);
Dictionary <T, int> fScore = new Dictionary <T, int>(this.equalityComparer);
MinPQ <T> openSet = new MinPQ <T>(new FScoreComparer(fScore), this.equalityComparer);
HashSet <T> closeSet = new HashSet <T>(this.equalityComparer);
openSet.Insert(start);
gScore.Add(start, 0);
fScore.Add(start, HeuristicDistance(start, goal));
while (!openSet.IsEmpty())
{
T current = openSet.DelMin();
if (this.equalityComparer.Equals(current, goal))
{
return(ReconstructPath(comeFrom, current));
}
closeSet.Add(current);
T[] neighbors = GetNeighbors(current);
foreach (T neighbor in neighbors)
{
if (closeSet.Contains(neighbor))
{
continue;
}
int gScoreTentative = gScore[current] + ActualDistance(current, neighbor);
// 新状态
if (!openSet.Contains(neighbor))
{
openSet.Insert(neighbor);
}
else if (gScoreTentative >= gScore[neighbor])
{
continue;
}
// 记录新状态
comeFrom[neighbor] = current;
gScore[neighbor] = gScoreTentative;
fScore[neighbor] = gScore[neighbor] + HeuristicDistance(neighbor, goal);
}
}
return(null);
}
/// <summary>
/// 获取堆的迭代器，元素以升序排列。
/// </summary>
/// <returns></returns>
public IEnumerator <Key> GetEnumerator()
{
MinPQ <Key> copy = new MinPQ <Key>(this.n);
for (int i = 1; i <= this.n; i++)
{
copy.Insert(this.pq[i]);
}
while (!copy.IsEmpty())
{
yield return(copy.DelMin()); // 下次迭代的时候从这里继续执行。
}
}
/// <summary>
/// 获取堆的迭代器，元素以升序排列。
/// </summary>
/// <returns>最小堆的迭代器。</returns>
public IEnumerator <Key> GetEnumerator()
{
var copy = new MinPQ <Key>(n);
for (var i = 1; i <= n; i++)
{
copy.Insert(pq[i]);
}
while (!copy.IsEmpty())
{
yield return(copy.DelMin()); // 下次迭代的时候从这里继续执行。
}
}
