Abstract
We propose a novel algorithm based on random graphs to construct minimal perfect hash functions h. For a set of n keys, our algorithm outputs h in expected time O(n). The evaluation of h(x) requires two memory accesses for any key x and the description of h takes up 1.15n words. This improves the space requirement to 55% of a previous minimal perfect hashing scheme due to Czech, Havas and Majewski. A simple heuristic further reduces the space requirement to 0.93n words, at the expense of a slightly worse constant in the time complexity. Large scale experimental results are presented.
This work was supported in part by GERINDO Project–grant MCT/CNPq/CT-INFO 552.087/02-5, CAPES/PROF Scholarship (Fabiano C. Botelho), FAPESP Proj. Tem. 03/09925-5 and CNPq Grant 30.0334/93-1 (Yoshiharu Kohayakawa), and CNPq Grant 30.5237/02-0 (Nivio Ziviani).
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Botelho, F.C., Kohayakawa, Y., Ziviani, N. (2005). A Practical Minimal Perfect Hashing Method. In: Nikoletseas, S.E. (eds) Experimental and Efficient Algorithms. WEA 2005. Lecture Notes in Computer Science, vol 3503. Springer, Berlin, Heidelberg. https://doi.org/10.1007/11427186_42
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DOI: https://doi.org/10.1007/11427186_42
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