```
void connect(TreeLinkNode *root) {
if(!root)
return;
while(root -> left)
{
TreeLinkNode *p = root;
while(p)
{
p -> left -> next = p -> right;
if(p -> next)
p -> right -> next = p -> next -> left;
p = p -> next;
}
root = root -> left;
}
}
```