Let us create binary tree given in the above example
node * root = newNode ( 1 ) ; root -> left = newNode ( 2 ) ; root -> right = newNode ( 3 ) ; root -> left -> right = newNode ( 4 ) ; root -> right -> left = newNode ( 5 ) ; root -> right -> left -> left = newNode ( 6 ) ; printSingles ( root ) ; return 0 ; }