This is my answer to problem J of IEEEXtreme 5.0(problem set), I was there too but this problem slipped my team. And I was thinking of it after the competition, and found out on designing that for circuits like unbalanced(when there is a current flowing in the central resistor) Wheatstone Bridge, sequential and parallel systems of simplifying resistor circuits are some what hard to apply in an automated manner(I personally failed to even find any automated solution other than solving the equations themselves!).
Then I saw it! The problem says itself that it’ll only check resistor systems that are parallel or sequential. So here’s the code. It might be the slowest way to get it done, but it gets it done.