* Finally, check that the puzzle is _at least_ as hard as
* required, and indeed that it isn't already solved.
* (Calling map_solver with negative difficulty ensures the
- * latter - if a solver which _does nothing_ can't solve
- * it, it's too easy!)
+ * latter - if a solver which _does nothing_ can solve it,
+ * it's too easy!)
*/
memcpy(colouring2, colouring, n*sizeof(int));
if (map_solver(sc, graph, n, ngraph, colouring2,