Function to merge given two binary trees
Node * MergeTrees ( Node * t1 , Node * t2 ) { if ( ! t1 ) return t2 ; if ( ! t2 ) return t1 ; t1 -> data += t2 -> data ; t1 -> left = MergeTrees ( t1 -> left , t2 -> left ) ; t1 -> right = MergeTrees ( t1 -> right , t2 -> right ) ; return t1 ; }