How Do I Win Rock Paper Scissors Every Time | Hacker News Reader

How Do I Win Rock Paper Scissors Every Time

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38 pointstomerico11 comments

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There was a RPS programming competition which tested various algorithms against each other:

http://webdocs.cs.ualberta.ca/~darse/rsbpc.html

My favorite was Iocaine Powder. The strategy is explained in more detail here:

http://www.ofb.net/~egnor/iocaine.html

Iocaine is also a reference to a well known scene in The Princess Bride

http://www.imdb.com/title/tt0093779/quotes?qt0482733

That was a fun competition. A good friend won it the first year.

Number 4 makes absolutely no sense. Even if the authors presumption is correct (i.e., that the opponent will not throw a rock), countering with a rock still gives you only a 50% chance of winning and 50% chance of loss. If the presumption were correct, it would be better to counter with scissors. Then you get 50% chance of winning and 50%chance of tie.

Is there a tie?

It helps to be a good mentalist too:

http://www.youtube.com/watch?v=gOwzGBRTiEg

Interesting. The two first players all followed the same linear move order: player 1 : scissor -> rock -> paper -> scissor -> rock player 2 : paper -> scissor -> rock -> paper -> scissor player 3 : scissor

You'll notice he keeps suggesting his opponent's throws. He demonstrates the game to the first player with scissors, who then throws scissors. Then he demonstrates how "rock smashes scissors", so his opponent thinks "Rock!" and throws it. Later in the video, he flashes scissors for no apparent reason before a throw, with success.

Watch the video, he 'seeds' his opponents throughout.

I remember reading an article a while back about some World Championship of Rock Paper Scissors. The winner back then said that most players with a "strategy" eventually failed. The only thing he did was think of a random sequence before playing and then stick to it.

Also, for those who feel that standard RPS-3 is not challenging, there is always RPS-101 (of which RPS-3 is a mere subset)

http://www.umop.com/rps101.htm

#3 has been my strategy since childhood, and it works surprisingly well against people who don't know the trick.

There's an annual RPS tournament in Las Vegas with a $500 buy-in. Andy Bloch from MIT blackjack team and high stakes poker fame is one proud RPS champion. Pretty serious business!

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