PermRowCol Algorithm

Benchmarks on a 3\times 3 square grid and a 4 \times 4 square grid, taken from the PermRowCol paper [1], which shows significant improvements using reverse traversal (RT) to find improved CNOT routings. The benchmarks compare PermRowCol against SteinerGauss and RowCol. The fact that PermRowCol without RT sometime performs worse than RowCol suggests that the heuristic for choosing the rows and columns to be eliminated via the Hamming weight should be improved upon.