I saw this puzzle on Twitter by user @lilva_0419 and I personally feel that it is impossible to solve. Can you prove me wrong (or right)?
Rules (see Wikipedia):
- Connect every white circle with lines into a single network.
- Lines start at black dots and end on white circles (not black dots!)
- Lines can make 90 degree turns, but cannot intersect or branch off of each other.
- The number in the circles gives the number of turns the line (starting at this circle's black dot) makes before reaching a white circle.
[Begin Edit] Here is the actual wording of the rules from Wikipedia. This is just for future reference, the accepted answer is correct, but this should clarify why the creative "think-outside-the-box" answer by FibS would unfortunately not work here. I apologize for my unfortunate wording.:
- Draw a line from each white circle's black dot to another white circle, following the grid's horizontal and vertical markings.
- Lines cannot be drawn from a black dot to another black dot, nor can they be drawn from a white circle not at its black dot to a white circle not at its black dot.
- No crossing or branching of lines is acceptable. At the end, the drawn lines will connect all white circles to form a single, contiguous network.
- The number on the white circle dictates how many times the line you draw '''from its black dot''' must bend before it meets another white circle. [End Edit]
[Begin 2nd edit] Apparently the Wikipedia translation of the first rule now reads (emphasis mine):
Draw a line from each white circle's black dot to any white circle, following the grid's horizontal and vertical markings.
Thanks @edderiofer for pointing it out.
That further supports the accepted solution.
[End 2nd edit]
I see two options for me being wrong: I misunderstood/forgot a rule. Or I overlooked a possibility in the puzzle.
The reason I think this is impossible:
In the top left corner the two turn line can have its first turn after one or two steps. After two steps it can connect to multiple other circles with another turn, but it cuts off the blank circle in the top row (see Figure 1). Turning after just one step only leaves one possible connection through another turn: The left of the two circles in the third row from the top. However that needs to connect to the blank circle in the top row, which leaves no reachable circle for that very same blank circle to connect to (see Figure 2).
Figure 1: Part I of the reason I suspect the puzzle has no solution.
Figure 2: Part II of the reason I suspect the puzzle has no solution.