Free alloc'd memory

Signed-off-by: wmb <wmb@teknik.io>

main.c

@@ -70,6 +70,8 @@ bool trouver_solution_initiale(void)
 	for (i = 0; !ret && i < (size_t) n_clusters; ++i)
 		ret = (ret || cluster_empty[i]);
 
+	free(cluster_empty);
+
 	return !ret;
 }