You sank my battleship... with probability!

September 17, 2015 6:11 AM

Battleship Probability Calculator by C. Liam Brown. Finds the best squares to try during the game.
posted by Wolfdog (14 comments total)

Interesting. I always play by making an X on the battlefield starting with the center squares. I win a lot with people who don't know that I do this.
posted by Splunge at 6:20 AM on September 17, 2015 [1 favorite]

Yep, beat it in 38 moves.
posted by Splunge at 6:25 AM on September 17, 2015

I just was talking about this because my son and I played recently and got to turn 15 (29th move) without any hits. I wrote a program to calculate the probability, thinking like this:

- the ships take up 17 or 100 squares, so prob of first miss is 83/100.
- prob of a second miss is 82/99 (99 squares left)
- third miss is 81/98 (etc)
- multiply series of 14 fractions together
- multiply by itself since both players had this happen

I got 0.36% but I'm rusty on probability stuff. Did I do it right?
posted by freecellwizard at 6:42 AM on September 17, 2015

I got 0.36% but I'm rusty on probability stuff. Did I do it right?

That assumes that there is an equal probability of a ship being located at each square. But if you fire a shot at B2, C1, C3, and D2, you can be assured that there is absolutely no ship piece at C2 since even the smallest ship is 2 pegs long.
posted by dances with hamsters at 8:08 AM on September 17, 2015 [1 favorite]

Ooo, a cribbage discard bot!
posted by Earthtopus at 8:08 AM on September 17, 2015

Doesn't curse or crow at all, though.
posted by Wolfdog at 8:13 AM on September 17, 2015 [2 favorites]

There's other neat stuff, too; The discussion of the Trainyard game is a pretty fascinating read, but I was just particularly amused by the existence of the Battleship calculator.
posted by Wolfdog at 8:15 AM on September 17, 2015

I like the message for the autoplay option.

Autoplay on: Your moves are now being made by a drunken gerbil crawling on an iPad.
posted by sciatrix at 8:15 AM on September 17, 2015 [1 favorite]

Also, with autoplay, the turn off button is oh god please stop.
posted by Hactar at 9:10 AM on September 17, 2015

Good point, dances with hamsters. Interesting how it's theoretically best to aim at the middle, but only if your opponent doesn't know you know that. Also IRL people tend to space ships out, 3 vertical and 2 horizontal, hide them at the edges, etc. And no one ever sets up ships in a tight group like this:

xxxxx
xxxx/xx
xxx/xxx

I guess some of that is that if a ship doesn't adjoin others and your opponent hits it, and it's not at the edge, they have a 2/4 chance of guessing wrong on the next shot if it's a middle hit, and a 3/4 chance to guess wrong if it turns out they've hit the end of the ship.

Also, my 1970s/early 80s copy of the game was recently discovered in a box in a storage facility my mom had, and my kids are playing it all the time now! Just had to wipe it down a bit :-)
posted by freecellwizard at 9:47 AM on September 17, 2015

Battleship is a game that just wouldn't feel right if I wasn't playing with the classic red/blue set that I had as a kid. Of course, that version also had the most explicitly sexist box of any game I ever owned.
posted by benito.strauss at 9:56 AM on September 17, 2015 [6 favorites]

It sure does take a long time to re-calculate the probabilities.
posted by pahool at 1:33 PM on September 17, 2015

Battleship is a game that just wouldn't feel right if I wasn't playing with the classic red/blue set

A few years before Milton-Bradley came out with their plastic version, my father taught me how to play the game on paper.

Wiccahpeedia points out that "It is known worldwide as a pencil and paper game which dates from World War I. It was published by various companies as a pad-and-pencil game in the 1930s." My father probably learned it from one of those mags, or possibly from his future father-in-law, a WWI veteran.

Fall of 1966 I taught a few classmates. By Christmas half the school was spending lunch / recess playing Battleship on paper. Some created additional vessel types, like submarines and PT boats, or made MUCH bigger grids and expanded navies. . . . Then came the M-B plastic version; the entire school scoffed. This might be the only time I was ever even slightly 'popular'.
 
posted by Herodios at 2:16 PM on September 17, 2015 [2 favorites]

An earlier attempt. Wonder how the two correlate.
posted by d. z. wang at 7:34 PM on September 17, 2015