Note: Finding a length-constrained maximum-sum or maximum-density subtree and its application to logistics

  • Authors:
  • Hoong Chuin Lau;Trung Hieu Ngo;Bao Nguyen Nguyen

  • Affiliations:
  • Singapore Management University, Singapore 178902, Singapore;National University of Singapore, Singapore 119260, Singapore;National University of Singapore, Singapore 119260, Singapore

  • Venue:
  • Discrete Optimization
  • Year:
  • 2006

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Abstract

We study the problem of finding a length-constrained maximum-density path in a tree with weight and length on each edge. This problem was proposed in [R.R. Lin, W.H. Kuo, K.M. Chao, Finding a length-constrained maximum-density path in a tree, Journal of Combinatorial Optimization 9 (2005) 147-156] and solved in O(nU) time when the edge lengths are positive integers, where n is the number of nodes in the tree and U is the length upper bound of the path. We present an algorithm that runs in O(nlog^2n) time for the generalized case when the edge lengths are positive real numbers, which indicates an improvement when U=@W(log^2n). The complexity is reduced to O(nlogn) when edge lengths are uniform. In addition, we study the generalized problems of finding a length-constrained maximum-sum or maximum-density subtree in a given tree or graph, providing algorithmic and complexity results.