Hello everyone! Here is an interesting problem on math I need help with:
Given
a set S (size n <=20) ,say S[1..n]
m (m<=10^5) subsets of S ,say Sub[1...m]
p (p<=10^5) people, say P[1..p]
Definition of one assignment
For p person, each one choose a subset ( can be the same ), so that the union
of the p subsets is equal to S.
Try to count
The number of assignments
. (time limit: 5 seconds)