public static Node getLCA(Node p, Node q){
int pHeight = getHeight (p);
int qHeight = getHeight (q);
if (pHeight < qHeight)
return getLCAHelper (qHeight - pHeight, p, q);
else
return getLCAHelper (pHeight - qHeight, q, p);
}
private static int getHeight(Node node){
int height = 0;
while (node != null) {
node = node.parent;
height++;
}
return height;
}
private static Node getLCAHelper(int d, Node p, Node q){ //d=q-p, q is the deeper one, p is the upper one
for (int i = 0; i < d; i++) {
q = q.parent;
}
while (p != null && q != null) {
if (p == q)
return p;
p = p.parent;
q = q.parent;
}
return null;
}