Disjoint Set Union (DSU)

http://vn.spoj.com/problems/IOIBIN/ - solution - code

http://vn.spoj.com/problems/C11BC2/ - solution - code

http://vn.spoj.com/problems/PBCGANGS/ - solution - code

http://vn.spoj.com/problems/PBCPOINT/ - solution - code

http://www.spoj.com/problems/NITTROAD/ - vn - solution - code

http://vn.spoj.com/problems/VNEMPIRE/ - solution
http://vn.spoj.com/problems/VMST/ - solution