Median Selection Requires ( 2 + ) n Comparisons
نویسندگان
چکیده
Improving a long standing result of Bent and John, we obtain a (2+ )n lower bound (for some fixed > 0) on the number of comparisons required, in the worst case, for selecting the median of n elements. The new lower bound is obtained using a weight function that allows us to combine leaf counting and adversary arguments.
منابع مشابه
Selection Algorithms
Given a set X containing n distinct elements, and given a number 1 i n, we would like to nd the element whose rank in X is exactly i, i.e., the element of X larger than exactly i 1 elements of X and smaller than the other n i elements of X. In particular we are interested cases where i = n for some 0 < < 1. The median of X is the dn=2e-th element. Improving a long standing result of Sch onhage...
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