An experimental evaluation of navigation piles∗

A navigation pile, which can be used as a priority queue, is an extension of a selection tree. In a compact form the whole data structure requires only a linear number of bits in addition to the elements stored. In this paper, we study the practical efficiency of three different implementations of navigation piles and compare their efficiency against two implementations of binary heaps. The results of our experiments show that navigation piles are a good alternative to heaps when element moves are expensive—even if heaps store pointers to elements instead of elements. Based on the experimental comparison of the three navigationpile implementations it is clear that care should be taken when applying space saving strategies that increase the number of instructions performed. In addition to our experimental findings, we give a new and simple way of dynamizing a static navigation pile. Furthermore, we introduce a pointer-based navigation pile which is inherently dynamic in its nature and can be made to support deletions as well.