Sorted Linked List to Balanced BST

PROBLEM :

Given a Singly Linked List which has data members sorted in ascending order. Construct a Balanced Binary Search Tree which has same data members as the given Linked List.

Examples:

Input:  Linked List 1->2->3
Output: A Balanced BST
     2  
   /  \
  1    3


Input: Linked List 1->2->3->4->5->6->7
Output: A Balanced BST
        4
      /   \
     2     6
   /  \   / \
  1   3  4   7

Input: Linked List 1->2->3->4
Output: A Balanced BST
      3  
    /  \
   2    4
 /
1

Input:  Linked List 1->2->3->4->5->6
Output: A Balanced BST
      4  
    /   \
   2     6
 /  \   /
1   3  5  

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SIMPLE c++ IMPLEMENTATION :
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/*
typedef struct BST
{
int info ;
struct BST *left ;
struct BST *right ;
}tree ;

typedef struct NODE
{
int data ;
struct NODE *next ;
}node ;---------------------------------------------*/


tree* create_linklist_tree(node *head)
{
node *slow,*fast,*left,*right ;
tree *temp ;

if(head==NULL)
return NULL  ;

slow=head ;
fast=head->next ;

while(fast!=NULL&&fast->next!=NULL)
{
slow=slow->next ;
fast=fast->next->next ;
}

right=slow->next ;
slow->next=NULL ;

left=head ;

if(head!=slow)
while(left->next!=slow)
left=left->next ;
left->next=NULL ;

temp=(tree*)malloc(sizeof(tree)) ;
temp->info=slow->data ;

if(temp->info==head->data)
{
if(right==NULL)
temp->right=create_linklist_tree(NULL) ;
else
temp->right=create_linklist_tree(right) ;
temp->left=create_linklist_tree(NULL) ;
}
else
{
temp->right=create_linklist_tree(right) ;
temp->left=create_linklist_tree(head) ;
}

return temp ;
}

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