Figure 1
From: Solving a Hamiltonian Path Problem with a bacterial computer

A directed graph containing a unique Hamiltonian path. The seven nodes are connected with fourteen directed edges. The Hamiltonian Path Problem is to start at node 1, end at node 5, and visit each node exactly once while following the available edges. Adleman programmed a DNA computer to find the unique Hamiltonian path in this graph (1→4→7→2→3→6→5).