A talent contest has 8 contestants.Judges must award prizes for first,second,and third palces, with no ties.
(a) In how many different ways can the judges award the 3 prizes?
(b)How many different groups of 3 people can get prizes?
a 的答案为336 b56 说一下算法呀 谢谢啦 排列组合都忘了