ZOJ Problem Set - 1219
You are responsible for ordering a large pizza for you and your friends. Each of them has told you what he wants on a pizza and what he does not; of course they all understand that since there is only going to be one pizza, no one is likely to have all their requirements satisfied. Can you order a pizza that will satisfy at least one request from all your friends?
The pizza parlor you are calling offers the following pizza toppings; you can include or omit any of them in a pizza:
Your friends provide you with a line of text that describes their pizza preferences. For example, the line
reveals that someone will accept a pizza with onion, or without ham, or with pepperoni, and the line
indicates that someone else will accept a pizza that omits extra cheese, or Italian sausage, or diced garlic, or that includes anchovies or jalapenos.
The input consists of a series of pizza constraints.
A pizza constraint is a list of 1 to 16 topping constraint lists each on a line by itself followed by a period on a line by itself.
A topping constraint list is a series of topping requests terminated by a single semicolon.
An topping request is a sign character (+/-) and then an uppercase letter from A to P.
For each pizza constraint, provide a description of a pizza that satisfies it. A description is the string "Toppings:" and then a series of letters, in alphabetical order, listing the toppings on the pizza. So, a pizza with onion, anchovies, fresh broccoli and Canadian bacon would be described by:
If no combination toppings can be found which satisfies at least one request of every person, your program should print the string
"No pizza can satisfy these requests." on a line by itself starting in column 1.
Source: South Central USA 1997