A utility function to do inorder traversal of BST
void inorder ( struct Node * root ) { if ( root != NULL ) { inorder ( root -> left ) ; printf ( " Node ▁ : ▁ % d , ▁ " , root -> key ) ; if ( root -> parent == NULL ) printf ( " Parent ▁ : ▁ NULL ▁ STRNEWLINE " ) ; else printf ( " Parent ▁ : ▁ % d ▁ STRNEWLINE " , root -> parent -> key ) ; inorder ( root -> right ) ; } }