Data structure

unionFind.cpp

int uf[SIZE];

void init() {
  std::iota(uf, uf+SIZE, 0);
}

int root(int x) {
  int _x = x;
  while(x!=uf[x]) x = uf[x] /* = uf[uf[x]] */ ;
  return uf[_x] = x;
}

bool test(int x, int y) {
  return root(x) == root(y);
}

void join(int x, int y) {
  x = root(x); y = root(y);
  uf[min(x,y)] = uf[max(x,y)];
}