Traverse nodes at p ' s ▁ level ▁ and ▁ find ▁ and ▁ return ▁ ▁ ▁ the ▁ first ▁ node ' s first child
while ( temp != null ) { if ( temp . left != null ) { return temp . left ; } if ( temp . right != null ) { return temp . right ; } temp = temp . nextRight ; }