// HeapVal<T> extends Comparable<T> : find in HeapVal.java

public class coord implements HeapValue<coord>, java.io.Serializable
{
    int y, x;
    int estcost;      // total cost, including knowndist and estimate
    int knowndist;    // distance (cost) from source node, excluding estimate
    boolean interior = false; // coord on frontier or interior
    coord prev; // pointer to previous coordinate on path.

    public coord(int a, int b) {y=a; x=b;} //other vars set externally

    public void copy(coord B) // replace information with those from coord B,
    {                         // but retain heap index info.  This method should
	y = B.y;  x = B.x;    // be called when a better coord is found on the
	estcost = B.estcost;  // frontier "list"
	knowndist = B.knowndist;
	interior = B.interior;
	prev = B.prev;
    }//copy

    public boolean equals(Object oc) // conforms to old java specs
    {
	if (oc==null || !(oc instanceof coord)) return false;
	coord c = (coord)oc;
	return (x==c.x && y==c.y);
    }

    public int compareTo(coord c) // compares cost, not compatible with .equals
    {
	return estcost - c.estcost; // reverse comparison: want smallest first
    }

    // for HeapVal interface, allows repositioning once estcost changes
    protected int Hi;  // index in heap (for HeapAware interface)
    public int getIndex() { return Hi; }
    public void setIndex(int i) { Hi=i; }
} // coord