The Seven Bridges of Königsberg

The city of Königsberg in Prussia (now Kaliningrad, Russia) was built around two rivers with seven bridges. For years the residents tried to cross each bridge without crossing any of them more than once.

Leonhard Euler proved that it was impossible to cross all the bridges without repeating and laid the foundation for graph theory and modern topology at the same time.

The Rules

	This is you
	You can't cross rivers
	Only cross bridges once
	Visit each house
	Boats can cross rivers, but only from one side
	Cross color bridges to change your color
	Only visit color houses if you're the same color
	Some bridges only go in one direction

Tutorial Levels

1 2 3

Visit All The Houses

4 5 6 7 8 9 10 11 12 13 14 15

Cross All The Bridges and Visit All The Houses

16 17 18 19 20 21 22