Cheryl's birthday: Difference between revisions

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Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is.

Cheryl gave them a list of 10 possible dates:

Cheryl gave them a list of ten possible dates:

May 15, May 16, May 19

~~May~~ ~~15,~~ ~~May~~ 16, ~~May 19~~

June 17, June 18

~~June~~ 17, ~~June~~ 18

July 14, July 16

~~July~~ 14, ~~July~~ 16

August 14, August 15, August 17

Cheryl then tells Albert and Bernard separately the month and the day of the birthday respectively.

1) Albert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too.

2) Bernard: At first I don't know when Cheryl's birthday is, but I know now.

3) Albert: Then I also know when Cheryl's birthday is.

1) Albert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too.

;Task

2) Bernard: At first I don't know when Cheryl's birthday is, but I know now.

Write a computer program to deduce, by successive elimination, Cheryl's birthday.

3) Albert: Then I also know when Cheryl's birthday is.

;Related task:

* [[Sum and Product Puzzle]]

;Task

;References

Write a program ~~in your language~~ to deduce, by successive elimination, Cheryl's birthday.

;Referrences

* [https://en.wikipedia.org/wiki/Cheryl%27s_Birthday Wikipedia article] of the same name.

* [https://en.wikipedia.org/wiki/Tuple_relational_calculus, Tuple Relational Calculus]

;Related task:

* [[Sum and Product Puzzle]]