比较2D数组Java

Question

I'm trying to find out where the second array given will positioned in the first array but cant seem to convert then to string to find out where they will be:

public static void main(String[] args) {
    char i [][] = new char[][]{
            {'d', 's', 'l', 'e', 'i', 'g', 'h', 'e', 'i', 'j', 'a', 's', 'l', 'd', 'k', 'j'},
            {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'W', 'w', 'Z', 'Z', 'Z', 'W', '1', 'l', 'k'},
            {'h', 'i', 'j', 'k', 'l', 'm', 'n', 'Z', 'A', 'a', 'Z', 'a', 'Z', '2', 'i', 'n'},
            {'o', 'p', 'q', 'r', 's', 't', 'u', 'Z', 'Z', 'L', 'l', 'Z', 'Z', '3', 'i', 'v'},
            {'v', 'w', 'x', 'y', 'z', '1', '2', 'Z', 'd', 'Z', 'D', 'd', 'Z', '4', 'q', 'i'},
            {'3', '4', '5', '6', '7', '8', '9', 'o', 'Z', 'Z', 'o', 'O', 'Z', '5', 'b', 'v'},
            {'k', 'e', '8', '7', '8', '4', 'j', 'f', 'l', 'k', 'a', 'v', '8', '8', 'h', 'j'}
    };

    char w [][] = new char[][]{
            {'W', 'w', '.', '.', '.', 'W', '1'},
            {'.', 'A', 'a', '.', 'a', '.', '2'},
            {'.', '.', 'L', 'l', '.', '.', '3'},
            {'.', 'd', '.', 'D', 'd', '.', '4'},
            {'o', '.', '.', 'o', 'O', '.', '5'}
    };

    find(i, w);
}

    public static int[] find(char [][] image, char [][] waldo) {
    for (int i = 0; i < waldo.length; i++) {
        char[] largerCharArray= large[i];
        String largerString = new String(largerCharArray);

        //used for debug purposes
        char[] array = largerCharArray;

        char [] smallCharArray = small[i];
        String smallString = new String(smallCharArray);

        char[] array1 = smallCharArray;

        //beginning comparison
        if (largerString.indexOf(smallString) >= 0) {

           int temp = largerString.indexOf(smallString);
        }

        //debug purposes
        System.out.println(largerString.indexOf(smallString));
        System.out.println(Arrays.toString(array));
        System.out.println(Arrays.toString(array1));
    }
    //for debug purposes
    return null;
}

Answer 1

As I understand the task is to find a matching submatrix. If you replace dots with wildcards, it makes sense. So the smaller matrix is at the position (row = 2, column = 8) counting from 1.

Here is the code which searches for submatrix. I used regular expressions to match rows as strings:

public static int[] find(char [][] large, char [][] small) {
    outer: for (int i = 0; i < large.length - small.length; i++) {

        int column = -1;

        for (int j = 0; j < small.length ; j++) {
            String largerString = new String(large[i + j]);

            String smallString = new String(small[j]);

            Matcher matcher = Pattern.compile(smallString).matcher(largerString);

            if(!matcher.find()){
                continue outer;
            }

            int thisColumn = matcher.start();

            if(column != -1 && column != thisColumn){
                continue outer;
            }

            column = thisColumn;
        }

        System.out.printf("found it: %d, %d!", i, column);
    }

    //for debug purposes
    return null;
}

Answer 2

Try this code I've just finished, it may have some bugs, it will try to improve it. It doesn't use Strings.

private static int[] find(char[][] image, char[][] waldo) {
    int row = -1;
    int column = -1;
    char first_waldo = waldo[0][0]; // first char of waldo
    boolean continue1 = true; // this is used to avoid looping when the indexes tried are not a possible answer
    int size = waldo.length * waldo[0].length; // number of elements of waldo
    int cont = 0;

    for (int i = 0; i < image.length; i++) {
        for (int j = 0; j < image[i].length; j++) { // Looping over chars in image array
            char current = image[i][j]; // Current char of image array
            if (current == first_waldo) { // If true, this indexes (i, j) are a possible answer
                row = i; // Current image row
                column = j; // Current image column
                cont = 0; // Count of how many chars are matched
                for (int k = row; k < row + waldo.length; k++) {
                    for (int l = column; l < column + waldo[0].length; l++) { // Looping over
                                                       // the possible matching array in image
//                          System.out.println("Comparing " + image[k][l] + " with " + waldo[k - row][l - column]);
//                          System.out.println(k + " " + l);
                        if (waldo[k - row][l - column] == '.') { // If its a point, count as matching characters
                            cont++;
                            continue; 
                        }
                        if (image[k][l] != waldo[k - row][l - column]) { // If chars are different, it's not the answer
                            row = -1;
                            column = -1;
                            continue1 = false; // So it doesn't continue looping
                            break;
                        } else {
                            cont++; // If they are equals, count as matching characters
                        }
                    }
                    if (continue1 == false) { // To avoid overlooping when it's not the answer
                        continue1 = true; // Reset value
                        break;
                    }
                }
                if (cont == size) { // Is the number of matched charactes equal to the size of waldo?
                    int[] res = {row, column};
                    return res; // Return indexes
                }

            } else {
                row = -1;
                column = -1;
            }

        }
    }
    int[] res = {-1, -1};
    //      System.out.println("\n" + row +" , " +  column);
    return res; // Not answer

}