|V| = 12, components = 3

  component 0 (3 vertices): 0 1 2 
  component 1 (4 vertices): 3 4 5 6 
  component 2 (5 vertices): 7 8 9 10 11 

same-component queries, answered in O(1) from comp[]
  0 and 2: connected
  0 and 4: not connected
  4 and 6: connected
  8 and 11: connected
