近来在一本杂志上看到这样一道题 :题目　U ={1,2 ,… ,10 },A、B都是U的子集 ,若A ∩B =Φ ,称集合对 (A ,B)为“好集” ,问这样的好集有多少 ?解法一　用分类思想若A为空集 ,这样的好集共有C01 0 (C01 0+… +C1 01 0 ) ,若A有 1个元素 ,则这样的好集个数为C11 0 (C09+… +C99 Recently a magazine has seen such a problem: the title U = {1,2,...,10}, A, B are all subsets of U, if A ∩B = Φ, say the pair (A, B) For “good set”, how many such good sets are there? If the solution is a classification idea, if A is an empty set, such a good set has C01 0 (C01 0+... +C1 01 0 ). If A has 1 element, The number of such good sets is C11 0 (C09+... +C99