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Thread: Shuffling a 2D array

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    Default Shuffling a 2D array

    public class Puzzle {
        public static String[][] grid = new String[4][4];
     
        public static void setupGame(){
            int count = 1;
            for(int i=0;i<4;i++){
                for(int j=0;j<4;j++){
                    grid[i][j] = Integer.toString(count++);
                }
                grid[3][3] = "?";
     
            }
        }

    My array is populated by numbers from 1-15 with a "?" as the last element. I was wondering what would be the easiest way to shuffle this so that each time a button is pressed it shuffles each position?


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    Default Re: Shuffling a 2D array

    Do you want all 16 items in the array to be shuffled as if they were in a single array, or do you want what is in row to be shuffled only within that row or column?
    If all elements as in a single array, copy them to a single dim array and use the Collections shuffle method and then copy them back to the 2 dim.

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    Default Re: Shuffling a 2D array

    shuffled as in a single array, I'm not too sure how to get the vaulues from the 2dim array to the single however?

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    Default Re: Shuffling a 2D array

    Use a nested loop for the 2 dim and have a separate index for the one dim

    Why are you using a 2 dim array? With a little arithmetic you can use a one dim array almost as easily as a 2 dim array.

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    Default Re: Shuffling a 2D array

    I was using a 2dim as it sets up a 4x4 grid to find the values for the game

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    Default Re: Shuffling a 2D array

    You can simulate a 2 dim array with a one dim array by using an equation to compute the index given the row and column.
    Something like: ix = row*nbrcols + col (off the top of my head, I'm sure it needs some adjustment)

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    Default Re: Shuffling a 2D array

    You could do what I'm doing in that particular case, create an arraylist, pass the 2d array into it via for loops, then use Collections.shuffle();

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