Problems can be seen in many different ways along with different ways of solving them. On occasion there may be an obstacle to overcome her or there. Every person has different thought process or ways of solving problems.
I interpreted the problem as having to move animals to another location without them hurting one another. I had used was to first figure out in my head which animal should go first, which was the cat because the dog would not eat the mouse and the cat would. The second animal to go was the mouse and here is the tricky part on the way back from dropping off the mouse I took the cat back with me to get the dog. I left the cat and picked up the dog and took him to the other side with the mouse. Lastly I picked up the cat and took it across the river finishing the problem.
The problem was like a story I remember my mother telling me as a child where there were three animals that a fox wanted to get across the river, it gave options for which ones should go first but certain animals would hurt the others. The strategy I used was information retrieval and a little trial and error. This problem is just like that one you need to figure out the best way to accomplish the goal without losing any of the animals, ultimately deciding which animal should go first, second, and finally last. The problem was not extremely hard to solve, it did have its mind pulling parts.
The only obstacles I came across were the initial decision of which animal should go first because it was difficult to figure out how to do it without any harm...