Consider a road network G on which a set C of clients and a set S of servers are located. Optimal location query (OLQ) in road networks is to find a location such that when a new server is set up at this location, a certain objective function computed based on the clients and the servers serving the clients is optimized. In this paper, we study the OLQ with the MinSum objective function in road networks, namely the MinSum query. This problem has been studied before, but the state-of-the-art is still not efficient enough. We propose an efficient algorithm based on the two-level pruning technique. We also study the extension of the MinSum query problem, namely the optimal multiplelocation MinSum query. Since this extension is shown to be NP-hard, we propose a greedy algorithm. Moreover, we give an approximate guarantee for our solution. Extensive experiments on the real road networks were conducted to show the efficiency of our proposed algorithms.
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