Artifact 12244591e3a7308ea9d73326e9cdd03aab9e1376
//-------------------------------------------------------------
// Union-Find
// Balancing + Path-Compression : O(invAckermann)
//
// Verified by
// - SRM Member Pilot 2 Div1 LV2
//-------------------------------------------------------------
struct UnionFind
{
vector<int> uf, sz;
int nc;
UnionFind(int N): uf(N), sz(N,1), nc(N)
{ for(int i=0; i<N; ++i) uf[i] = i; }
int size()
{ return nc; }
int size(int a)
{ return sz[Find(a)]; }
int Find(int a)
{ return uf[a]==a ? a : uf[a]=Find(uf[a]); }
bool Union(int a, int b)
{
a = Find(a);
b = Find(b);
if( a != b )
{
if( sz[a] >= sz[b] ) swap(a, b);
uf[a] = b;
sz[b] += sz[a];
--nc;
}
return (a!=b);
}
};