There are N number of possible drinks.(n1,n2…)

Has C number of fixed customers.

Every customer has fixed favourite set of drinks.

Bartender has to create least possible number of drinks

to suffice need of all the customers

Example:

Cust1: n3,n7,n5,n2,n9

Cust2: n5

Cust3: n2,n3

Cust4: n4

Cust5: n3,n4,n3,n5,n7,n4

Output: 3(n3,n4,n5)

Need help on this question. If anyone can provide the approach or code it would be helpful in C++