Create a Circular Link List from a Given Binary Tree.

Create a Circular Link List from a Given Binary Tree.

struct node
{
 struct node* left;
 struct node* right;
 int data; 
}
typedef struct node* Node;

Node* B2L(node* root)
{
 if(!root) return NULL;
  
 Node* listA=B2L(root->left);
 Node* listB=B2L(root->right);
 return append(listA,root,listB);
}

Node* append(Node* listA, Node* root, Node* listB)
{
 if(listA)
  {
   root->next=listA;
   root->prev=listA->prev;
   listA->prev=root;
   root=listA;
  }

 if(listB)
  {
   Node* tail=listB->prev;
   root->prev->next=listB;//tail
   listB->prev->next=root;//tail
   listB->prev=root->prev;//head
   root->prev=tail;
  }
return root;
}