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Searching semisorted tables. (English) Zbl 0578.68049

A ”semisorted table” is a one-dimensional array containing n data, which are not necessarily sorted, but can appear in p different permutations of the ascending order. We consider the problem of searching in such a table without knowing, in which one of the p permutations the data are stored (SST). It is shown that any deterministic search algorithm for SST needs at least \(\sqrt{^{n}p}\) comparisons in the worst case. This lower bound is generalized to average case performance even for nondeterministic algorithms. Some examples are given where the lower bound is tight.

MSC:

68P10 Searching and sorting
68Q25 Analysis of algorithms and problem complexity
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