Update fill.c

fill.c

@@ -28,5 +28,5 @@ int main(){
     printf("The solution of Sudoku matrix:\n");
     sudokuPrint(*pres);
     end=clock();
-    printf("dur:%ldms\n", end-st);
+    printf("dur:%.1lfms\n", ((double)end-st)/CLOCKS_PER_SEC*1000);
 }