I'm Puzzled

This is a componet of The Old College Try puzzle in Sunday's edition of the NYTimes that I have attempted to solve. I was able to solve all other componets of the puzzle, guess the answer word for the above computer science puzzle and complete the "final exam" successfully; however, I still don't get this puzzle. I don't see how you can have two sides marked on the 2 in the second row and then two sides marked on the 2 in the third row and one side marked on the 1 next the the 2 in the third row and make a completed grid similar to the example. I guess I am just missing something. Otherwise, I thought the puzzle was easier than others that have been printed.