An Improved Algorithm For Finding A Length-constrained Maximum-density Subtree In A Tree

摘要

Given a tree T with weight and length on each edge, as well as a lower bound L and an upper bound U, the so-called length-constrained maximum-density subtree problem is to find a maximum-density subtree in T such that the length of this subtree is between L and U. In this study, we present an algorithm that runs in O(nU log n) time for the case when the edge lengths are positive integers, where n is the number of nodes in T, which is an improvement over the previous algorithms when U = Ω(log n). In addition, we show that the time complexity of our algorithm can be reduced to O(nL log n/L), when the edge lengths being considered are uniform.