The grid has a problem
4 edges have had their signs flipped. Click the edges to flip their sign.
Goal
Get all circles to 0: the vacuum state.
The circles detect issues
Each circle sums the edges walking around in a loop.
Travelling right/down adds the edge value, travelling left/up subtracts it.
Note that loops share edges with each other. Right for one loop might be left for another.
Click a circle to see its loop with normalized values (which will add up to the circle value).
I'm confused?
Lower the flip count to simplify the puzzle.