Unravel the Rope
Is it true that for every closed curve in the plane, you can use a rope to recreate the layout, so that the rope can be untangled?
Said otherwise, you have to determine at each intersection point of the closed curve, which of the two parts goes over and which one goes under, so that there aren’t any knots in the resulting rope.
SOLUTION
Start from any point of the curve and keep moving along it, so that at each non-visited intersection you go over, until you get back to where you started from.
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