Hi, Ok so i solved this problem by converting the map to a graph and then merging all vertices that are in the same country and then i found the minimum connecting subgraph for the 3 vertices. ok now the strange part is that in test case 5, n and m are 1000 and my solution passes this test but in test case 19 n, m are 995 and 997 but i get Memory Limit Exceeded and i cant understand why. i would be grateful if someone helped me out. Thanks...
The link to my submission: 13957392
The link to the problem: 590C - Три государства
My guess is people aren't willing to help because your code is quite long. I'm not sure what's wrong with it, kind of for the same reason, but I'll pitch in some suggestions:
For reference, here's my fixed submission, maybe it helps. http://mirror.codeforces.com/contest/590/submission/13855446