Should return whether or not a the current solution instance is_feasible.
In our case, I think that we should check that the unused set is empty.
Optionally, we could also check that the length of the used set is the same as n and check if path contains a duplicate city.
Should return whether or not a the current solution instance is_feasible.
In our case, I think that we should check that the unused set is empty. Optionally, we could also check that the length of the used set is the same as
nand check if path contains a duplicate city.