/// <summary>
/// Calculates heuristic distance to target node.
/// </summary>
/// <param name="dataPos">The data node position.</param>
/// <param name="emptyPos">The empty node.</param>
/// <param name="targetNodePos">The target node.</param>
/// <returns>The heuristic distance to target node.</returns>
public static int CalcF(X_Y dataPos, X_Y emptyPos, X_Y targetNodePos)
{
var adjustedTargets = new X_Y[]
{
new X_Y()
{
X = dataPos.X - 1, Y = dataPos.Y
},
new X_Y()
{
X = dataPos.X + 1, Y = dataPos.Y
},
new X_Y()
{
X = dataPos.X, Y = dataPos.Y + 1
},
new X_Y()
{
X = dataPos.X, Y = dataPos.Y - 1
},
};
var fs = adjustedTargets.Select(t =>
{
var distanceTargetY = Math.Abs(dataPos.Y - targetNodePos.Y);
var distanceEmptyY = Math.Abs(t.Y - targetNodePos.Y);
var distanceTargetX = Math.Abs(dataPos.X - targetNodePos.X);
var distanceEmptyX = Math.Abs(t.X - targetNodePos.X);
var f = CalcFAdjusted(distanceTargetX, distanceTargetY, distanceEmptyX, distanceEmptyY);
return(new { h = emptyPos.CalcManhattanDistance(t), f });
})
.OrderBy(x => x.h)
.ThenBy(x => x.f);
var target = fs.First();
return(target.h + target.f);
}
