23dfcca431 2011-02-23        kinaba: //-------------------------------------------------------------
23dfcca431 2011-02-23        kinaba: // Union-Find
23dfcca431 2011-02-23        kinaba: //   Balancing + Path-Compression : O(invAckermann)
23dfcca431 2011-02-23        kinaba: //
23dfcca431 2011-02-23        kinaba: // Verified by
23dfcca431 2011-02-23        kinaba: //   - SRM Member Pilot 2 Div1 LV2
23dfcca431 2011-02-23        kinaba: //-------------------------------------------------------------
23dfcca431 2011-02-23        kinaba: 
23dfcca431 2011-02-23        kinaba: struct UnionFind
23dfcca431 2011-02-23        kinaba: {
23dfcca431 2011-02-23        kinaba: 	vector<int> uf, sz;
23dfcca431 2011-02-23        kinaba: 	int nc;
23dfcca431 2011-02-23        kinaba: 
23dfcca431 2011-02-23        kinaba: 	UnionFind(int N): uf(N), sz(N,1), nc(N)
23dfcca431 2011-02-23        kinaba: 		{ for(int i=0; i<N; ++i) uf[i] = i; }
23dfcca431 2011-02-23        kinaba: 	int size()
23dfcca431 2011-02-23        kinaba: 		{ return nc; }
d52cf3ca74 2012-12-12        kinaba: 	int size(int a)
d52cf3ca74 2012-12-12        kinaba: 		{ return sz[Find(a)]; }
23dfcca431 2011-02-23        kinaba: 	int Find(int a)
23dfcca431 2011-02-23        kinaba: 		{ return uf[a]==a ? a : uf[a]=Find(uf[a]); }
da169a2bbe 2015-06-06        kinaba: 		// Semi-compression w.o. recursion.
da169a2bbe 2015-06-06        kinaba: 		//{ while(uf[a] != a) a=uf[a]=uf[uf[a]]; return a; }
23dfcca431 2011-02-23        kinaba: 	bool Union(int a, int b)
23dfcca431 2011-02-23        kinaba: 		{
23dfcca431 2011-02-23        kinaba: 			a = Find(a);
23dfcca431 2011-02-23        kinaba: 			b = Find(b);
23dfcca431 2011-02-23        kinaba: 			if( a != b )
23dfcca431 2011-02-23        kinaba: 			{
23dfcca431 2011-02-23        kinaba: 				if( sz[a] >= sz[b] ) swap(a, b);
23dfcca431 2011-02-23        kinaba: 				uf[a] = b;
23dfcca431 2011-02-23        kinaba: 				sz[b] += sz[a];
23dfcca431 2011-02-23        kinaba: 				--nc;
23dfcca431 2011-02-23        kinaba: 			}
23dfcca431 2011-02-23        kinaba: 			return (a!=b);
23dfcca431 2011-02-23        kinaba: 		}
23dfcca431 2011-02-23        kinaba: };