New common ancestor problems in trees and directed acyclic graphs
نویسندگان
چکیده
We derive a new generalization of lowest common ancestors (LCAs) in dags, called the lowest single common ancestor (LSCA). We show how to preprocess a static dag in linear time such that subsequent LSCA-queries can be answered in constant time. The size is linear in the number of nodes. We also consider a “fuzzy” variant of LSCA that allows to compute a node that is only an LSCA of a given percentage of the query nodes. The space and construction time of our scheme for fuzzy LSCAs is linear, whereas the query time has a sub-logarithmic slow-down. This “fuzzy” algorithm is also applicable to LCAs in trees, with the same complexities.
منابع مشابه
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عنوان ژورنال:
- Inf. Process. Lett.
دوره 110 شماره
صفحات -
تاریخ انتشار 2010