connect next node of binary tree (not a complete binary tree)

Given a binary tree

    struct TreeLinkNode {
      TreeLinkNode *left;
      TreeLinkNode *right;
      TreeLinkNode *next;
    }

Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL.

Initially, all next pointers are set to NULL.

For example,
Given the following binary tree,

         1
       /  \
      2    3
     / \    \
    4   5    7

After calling your function, the tree should look like:

         1 -> NULL
       /  \
      2 -> 3 -> NULL
     / \    \
    4-> 5 -> 7 -> NULL

 TreeLinkNode* nextFind(TreeLinkNode *root)
 {
  if(!root)
   return NULL;
  root = root->next;
  TreeLinkNode *retAdd = NULL;
  while(root)
  {
   if(root->left)
   {
    retAdd = root->left;
    break;
   }

   if(root->right)
   {
    retAdd = root->right;
    break;
   }


   root = root->next;
  }

  return retAdd;
 }


 void connectR(TreeLinkNode * root)
 {
  if(!root)
   return;

  if(root->left)
  {
   if(root->right)
   {
    root->left->next = root->right;
    root->right->next = nextFind(root);
    connectR(root->right);
   }
   else
   {
    // no right
    root->left->next = nextFind(root);
    connectR(root->right);
   }

   connectR(root->left);
  }

  else if(root->right)
  {
   root->right->next = nextFind(root);
   connectR(root->right);
  }

  else
  {
   connectR(nextFind(root));
  }
 }

 

 void connect(TreeLinkNode * root) {
  if(!root)
   return;

  root->next = NULL;
  connectR(root);
}