Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A greedy approximation algorithm for the longest path problem in
  undirected graphs   In graph theory, the longest path problem is the problem of finding a simple
path of maximum length in a given graph. For some small classes of graphs, the
problem can be solved in polynomial time [2, 4], but it remains NP-hard on
general graphs, since it includes the Hamiltonian path problem as a special
case [3]. Motivated by finding a simple, quick algorithm for finding long paths
in large graphs, in this paper we show a greedy algorithm with a time
complexity of O(n^2 (n+m)), where n is the number of the vertices and m is the
number of edges.

7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ