A utility function to do inorder traversal of BST
static void inorder ( Node root ) { if ( root != null ) { inorder ( root . left ) ; System . out . print ( " Node ▁ : ▁ " + root . key + " ▁ , ▁ " ) ; if ( root . parent == null ) System . out . println ( " Parent ▁ : ▁ NULL " ) ; else System . out . println ( " Parent ▁ : ▁ " + root . parent . key ) ; inorder ( root . right ) ; } }