DBSPT-CIRCULAR-PO ALGORITHM:

The DBSPT-Circular-PO algorithm is an extension to the DBSPT-Circular algorithm in which the tree is forced to be of minimum possible height, logB n. The PO in this algorithm name stands for post optimization. After the DBSPT-Circular algorithm has completed, the tree is compacted by examining the tree in breadth-first search
order, starting with the root. Any vertex encountered that has an out-degree < B is brought up to an out-degree of B by promoting a sub-tree. If the node being examined
is at level i, sub-trees rooted in levels greater than i + 2 are considered potential children. The promotion which causes the least increase to average-latency is the transfer enacted in the current tree. This procedure guarantees a final tree of minimum height, at the expense of increased average-latency.