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lazypeterson
October 27th, 2009, 06:37 AM
I'm working on a basic game where the user is given a U.S. state and then is asked to identify the capital (via a text box).

Right now, I've got it to where it will pick a state at random and tell you if you've guessed correctly or not. However, many states will repeat before going through all fifty.

As a beginning programmer, I'm a little bit stumped. I was thinking, perhaps I could go through the list randomly, add each array number that's already been hit to a whole other array... and then compare each randomly chosen element in the array with the numbers in the new array beforehand to make sure the state has not been done. That sounds a little overkill to me, I can't help but feel there's an easier way to do this.

I searched around for some algorithms relating to this with no luck. Any help would be greatly appreciated!!!!

Dark_Stang
October 27th, 2009, 07:05 AM
It would be easier to do a linked list and just remove that state from the list after it has been guessed correctly.

NovaAesa
October 27th, 2009, 07:10 AM
What I would do, is randomly permutate the array using the Fisher-Yates algorithm, then just go through the array in a linear fashion.

http://en.wikipedia.org/wiki/Fisher–Yates_shuffle

Easy!

Arndt
October 27th, 2009, 10:23 AM
I'm working on a basic game where the user is given a U.S. state and then is asked to identify the capital (via a text box).

Right now, I've got it to where it will pick a state at random and tell you if you've guessed correctly or not. However, many states will repeat before going through all fifty.

As a beginning programmer, I'm a little bit stumped. I was thinking, perhaps I could go through the list randomly, add each array number that's already been hit to a whole other array... and then compare each randomly chosen element in the array with the numbers in the new array beforehand to make sure the state has not been done. That sounds a little overkill to me, I can't help but feel there's an easier way to do this.

I searched around for some algorithms relating to this with no luck. Any help would be greatly appreciated!!!!

If rearranging the array is not a problem, you can do it like this: get a random number i between 1 and N, pick state i, do something with it, then exchange state N and i. Set N = N-1. Do again until N == 0.

kavon89
October 27th, 2009, 01:37 PM
Use an ArrayList (http://www.j2ee.me/javase/6/docs/api/java/util/ArrayList.html). Remove the state that is chosen [make sure you use the list's current size for the nextInt() in your loop], or use two of them and add the state to the other list while removing it from the other if you need to use the chosen states for something else.

unknownPoster
October 27th, 2009, 04:24 PM
What I would do, is randomly permutate the array using the Fisher-Yates algorithm, then just go through the array in a linear fashion.

http://en.wikipedia.org/wiki/Fisher–Yates_shuffle (http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle)

Easy!

I really like this approach, especially because of the O(n) complexity.

/me is an algorithms geek.