Following the selection of the cluster J selected based on the average score and standard deviation for defining a policy, one final node (j selected ) is selected from the chosen cluster using the selection policies of the node candidates. In this search, clustering is performed based on the matching of molecular bonding patterns of the 3D structure of each node vi . Figures worsens when hierarchical selection is applied (from the brown to the black lines). Although the TS's search performance also decreases with the application of hierarchical selection, this decrease is less pronounced (from the red to the orange lines). In contrast, in the Strecker reaction dataset, hierarchical selection improves Random's and TS's search performances across all the iteration steps. We can anticipate that the initial cluster selection enhances the search for a more diverse set of structures in terms of cluster space, with a tendency to select a node in the cluster with fewer nodes and hard to select a node in the cluster with more nodes. As demonstrated by the analysis of the node selection mechanism in Section 4-2, selecting nodes with minimum path lengths of 1 and 2 is critical for achieving the goal.