The Hamiltonian
Circuit
Inspired by a game devised by the Irish mathematician Sir William Rowan Hamilton in 1859, the Hamiltonian Circuit is based on graph theory. Think of it as a giant maze. To create the circuit, you have to visit each vertex in the grid exactly once, never going backwards or crossing a path.
There is only ever one solution per circuit. The more complex the circuit, the harder it is to solve—like this one, for instance.


i2 = j2 = k2 = ijk = −1