[Update: The winners have been posted on my home node, along with a simple demo program which contains their code.]

Tenpin bowling, to be precise (there are many bowling games with a variety of scoring rules). This was partly inspired by a chatterbox discussion many weeks ago. For those who have never had the pleasure, tenpin bowling is a game which consists of 10 frames, in each of which you are given two tries to knock down 10 pins.* If you succeed on the first try, it's a strike. If you succeed with the second try, it's a spare, otherwise you blew it. :)

Scoring per frame works as follows:
Strike ('X'): 10 + the # of pins knocked down on the next 2 balls
Spare ('/'): 10 + the # of pins knocked down on the next ball
Else: The sum of the pins knocked down in two tries

The maximum score in any one frame is 30. The minimum is 0. A game consisting of all strikes (AKA a 'perfect game') is 300. The 10th frame is "special". If a strike is thrown on the first ball, then the player gets two more throws (to satisfy the scoring rule above). Likewise, if a spare is achieved on the second ball of the 10th frame, then the player gets one more throw. This means that a game may consist of as few as 11 balls thrown (9 strikes in first 9 frames, then no strike or spare in the 10th) to a maximum of 21. So, given these rules, construct some code to score a game.

You can assume that you will get an array containing the pinfall for 10 frames, e.g.

my @b = ('5', '/', '6', '3', 'X', 'X', '7', '0', '4', '3',
'X', '4', '/', '8', '1', '3', '/', '6');
[download]

(Update: The above data represents a game of 146)

Or, you can handle getting the pinfall data any way you want. I don't care, so long as the code calculates scores correctly.

Thanks to chipmunk and tilly for corrections/suggestions

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*It also consists of nasty rented shoes and ugly shirts, the horror of which is only partially offset by the availability of bad beer