/*
knakul853
*/

class Solution {
public:
    Node* connect(Node* root) {

        if ( !root ) return NULL;

        if(root->left)
            root->left->next = root->right;
        if(root->right && root-> next)
        {
            root->right->next = root->next->left;
        }


        connect( root->left );
        connect( root->right );
        return root;
    }
};