Q: How to calculate domino-chain for integer pairs? The problem I'm facing is more like of algorithmic nature.
Let's say that I have a list of pair objects containing integers. Is there a way to sort the list so that the second part of the pair is equal to first part of the next pair?
For instance given this list of pairs:
 A = Pair(2,1),Pair(2,3),Pair(1,3).
After sorting the list becomes:
A = Pair(1,3), Pair(3,2),Pair(2,1).
As you can see it is allowed to change the order of values inside the pair like the Pair(2,3) which became Pair(3,2).
I though about using comparator or comparable interfaces but they dont cover complex cases like the above.
