t、u、d是digit number , different from each other,都是在1到9的,问the closest of the largest difference between the greatest S and the least S
有选项50 60 70 80 90,
"the closest of the largest difference between the greatest S and the least S"这部分不是很理解,意思是不是问在t,u,d取值一定的情况下,排列不同的情况下,最大S和最小S的最小差别吗??怎么算出来的呢??希望达人讲解一下,万分感谢啊