Parallel algorithms for a depth first search and a breadth first search

Two graph search problems are considered in a parallel computational environment. In this paper, we use the shortest path algorithm as a useful parallel computational technique. Based on the parallel shortest path algorithm presented by Dekel [8], we develop a parallel breadth first search algorithm for general graphs and a parallel depth first search algorithm for acyclic digraphs which run in time O(logd-logn) using 0(n 2[n/log n]) processors. For a breadth first search, the resulting algorithm is the same with that of Ghosh and Bhattacharjee [9]. But the difference between them is that the algorithm presented in [9] is based on the parallel breadth first search algorithm for trees while our algorithm is based on the shortest path algorithm. Furthermore, the algorithms presented in this paper have a unified algorithm structure.