Filling a 2D array with specific and random integers / chars

Question

I have to create a 2D array that I print out, however I am struggling trying to include all the specific details. I am given the number of rows and columns via user input, then must print an array with "S" at the top left and "D" at the bottom right, filled with random "#"'s and random numbers. Numbers are randomly generated within the range of [1, 100] inclusively, while the total number of "#" cannot exceed the 1/3 of the total size of the matrix.

However, I'm rather stuck and don't know where to go on my code...

Code:

public void drawMaze(int numRows, int numCols) {

    int[][] mazeArray = new int[numRows][numCols];
    Random  random = new Random(); 

    // Starting Point
    mazeArray[0][0] = "S";
    // Destination Point
    mazeArray[numRows][numCols] = "D";

    for (int i = 0; i < mazeArray.length; i++) {
        for (int j = 0; j < mazeArray[i].length; j++) {
            mazeArray[i][j] = (int)(Math.random()*10);
        }
    }

}

Help would be appreciated!

Answer 1

This could be something like this:

public void drawMaze(int numRows, int numCols) {
    String[][] mazeArray = new String[numRows][numCols];
    Random random = new Random();
    for (int i = 0; i < mazeArray.length; i++) {
        for (int j = 0; j < mazeArray[i].length; j++) {
            int result = 1 + random.nextInt(200);
            if (result > 100) {
                mazeArray[i][j] = "#";
            } else {
                mazeArray[i][j] = Integer.toString(result);
            }
        }
    }
    //starting point
    mazeArray[0][0] = "S";
    //destination point
    mazeArray[numRows-1][numCols-1] = "D";
    for (int i = 0; i < mazeArray.length; i++) {
        for (int j = 0; j < mazeArray[i].length; j++) {
            System.out.print(String.format("%4s", mazeArray[i][j]));
        }
        System.out.println();
    }
}

200 is just a hardcoded value. You may make it dependent on arguments of the method.
4 in System.out.print(String.format("%4s", mazeArray[i][j])); is responsible for spacing (can be changed to another integer, of course).

Answer 2

You should not go for each field after another. Better way could be to fill the fields randomly and leaving 1/3 of your fields empty to be filled with #.

• Fill complete array (mazeArray) with "#"
• Calculate your overall fields to fill with numbers (numRows*numCols*2/3)=maxFields
• Setup a 1-dimensional array (fieldsToFill) filled with 0 to maxFields, incrementing
• Now choose randomly a number of the fieldsToFill and fill up this field pos in your 2-dim array mazeArray and delete that element from fieldsToFill

This way you get your maze filled more randomly.