如何在java中以不同的方式读取矩阵数组？

zzwlnbp8  于 2021-07-06  发布在  Java
关注(0)|答案(3)|浏览(501)

我有一个8x8矩阵阵列。我想读取如图所示的矩阵值（元素）。我能做什么？
我定义了这样的数组。

public static void main(String args[]) {
    int[][] myArray = new int[8][8];

    int start = 0;

    for (int i = 0; i<8; i++){
        for (int j = 0; j<8; j++) {
            myArray[i][j] = start;
            start++;
        }
    }
}

JavaArraysMatrix

3条答案

按热度按时间
kninwzqo

kninwzqo1#

这是我的解决办法。代码包含解释遍历算法的注解。

public class MatrixTraversal {
    private static int[][]  matrix;

    private static void displayElement(int row, int col, int length, int count) {
        System.out.printf("%" + length + "d. Next  element [%" + length + "d][%" + length + "d] = %" + length + "d%n",
                          (count + 1),
                          row,
                          col,
                          matrix[row][col]);
    }

    private static void displayMatrix() {
        int length = getLength();
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                if (j > 0  &&  j < matrix[i].length) {
                    System.out.print(" ");
                }
                System.out.printf("%" + length + "d", matrix[i][j]);
            }
            System.out.println();
        }
        System.out.println();
    }

    private static int getLength() {
        int rows = matrix.length;
        int cols = matrix[0].length;
        int number = rows * cols;
        int length = (int) (Math.log10(number) + 1);
        return length;
    }

    private static void initMatrix(int rows, int cols) {
        System.out.printf("rows = %d , columns = %d%n", rows, cols);
        System.out.println();
        if (rows > 0  &&  cols > 0) {
            matrix = new int[rows][cols];
            for (int row = 0; row < rows; row++) {
                for (int col = 0; col < cols; col++) {
                    matrix[row][col] = (row * cols) + col;
                }
            }
            displayMatrix();
        }
        else {
            throw new IllegalArgumentException("rows and columns must both be positive");
        }
    }

    // Algorithm:
    // 1. Start at first row, last column.
    // 2. Go to same row, column to left.
    //    a. If can't go left, go down one row, i.e. same column, next row.
    //    b. If can't go left, go to step 3.
    // 3. Go diagonally down and to the right until reach either last row or last column.
    //    a. If can't go diagonally down and to the right, go to 4.
    // 4. Go to same column, next row.
    //    a. If can't go down, go left, i.e. same row, column to left.
    //    b. If can't go left, go to step 5.
    // 5. Go diagonally up and to the left until reach either first row or first column.
    //    a. If can't go diagonally up and to the left, go to 6.
    // 6. Go back to step 2.
    // 7. Finish at last row, first column.
    private static void traverse() {
        int length = getLength();
        int total = matrix.length * matrix[0].length;
        System.out.println("Total = " + total);
        int row = 0;
        int col = matrix[row].length - 1;
        System.out.println("Start col = " + col);
        int count = 0;
        System.out.printf("%" + length + "d. First element [%" + length + "d][%" + length + "d] = %" + length + "d%n",
                          1,
                          row,
                          col,
                          matrix[row][col]);
        count++;
        while (count < total) {
            if (col - 1 >= 0) {
                col--;
                displayElement(row, col, length, count);
                count++;
            }
            else {
                if (row < matrix.length - 1) {
                    row++;
                    displayElement(row, col, length, count);
                    count++;
                }
            }
            while (row < matrix.length - 1  &&  col < matrix[row].length - 1) {
                row++;
                col++;
                displayElement(row, col, length, count);
                count++;
            }
            if (row < matrix.length - 1) {
                row++;
                displayElement(row, col, length, count);
                count++;
            }
            else {
                if (col - 1 >= 0) {
                    col--;
                    displayElement(row, col, length, count);
                    count++;
                }
            }
            while (row > 0  &&  col > 0) {
                row--;
                col--;
                displayElement(row, col, length, count);
                count++;
            }
        }
    }

    /**
     * Requires following two <tt>java</tt> command arguments (in listed order):
     * <ol>
     * <li>number of rows in matrix</li>
     * <li>number of columns in matrix</li>
     * </ol>
     * 
     * @param args - <tt>java</tt> command arguments.
     */
    public static void main(String[] args) {
        if (args.length > 1) {
            int rows = Integer.parseInt(args[0]);
            int cols = Integer.parseInt(args[1]);
            initMatrix(rows, cols);
            traverse();
        }
        else {
            System.out.println("ARGS: <# of rows in matrix> <# of columns in matrix>");
        }
    }
}

在不同维度上进行测试，包括一行多列和一列多列。这是8x8矩阵的输出。

rows = 8 , columns = 8

 0  1  2  3  4  5  6  7
 8  9 10 11 12 13 14 15
16 17 18 19 20 21 22 23
24 25 26 27 28 29 30 31
32 33 34 35 36 37 38 39
40 41 42 43 44 45 46 47
48 49 50 51 52 53 54 55
56 57 58 59 60 61 62 63

Total = 64
Start col = 7
 1. First element [ 0][ 7] =  7
 2. Next  element [ 0][ 6] =  6
 3. Next  element [ 1][ 7] = 15
 4. Next  element [ 2][ 7] = 23
 5. Next  element [ 1][ 6] = 14
 6. Next  element [ 0][ 5] =  5
 7. Next  element [ 0][ 4] =  4
 8. Next  element [ 1][ 5] = 13
 9. Next  element [ 2][ 6] = 22
10. Next  element [ 3][ 7] = 31
11. Next  element [ 4][ 7] = 39
12. Next  element [ 3][ 6] = 30
13. Next  element [ 2][ 5] = 21
14. Next  element [ 1][ 4] = 12
15. Next  element [ 0][ 3] =  3
16. Next  element [ 0][ 2] =  2
17. Next  element [ 1][ 3] = 11
18. Next  element [ 2][ 4] = 20
19. Next  element [ 3][ 5] = 29
20. Next  element [ 4][ 6] = 38
21. Next  element [ 5][ 7] = 47
22. Next  element [ 6][ 7] = 55
23. Next  element [ 5][ 6] = 46
24. Next  element [ 4][ 5] = 37
25. Next  element [ 3][ 4] = 28
26. Next  element [ 2][ 3] = 19
27. Next  element [ 1][ 2] = 10
28. Next  element [ 0][ 1] =  1
29. Next  element [ 0][ 0] =  0
30. Next  element [ 1][ 1] =  9
31. Next  element [ 2][ 2] = 18
32. Next  element [ 3][ 3] = 27
33. Next  element [ 4][ 4] = 36
34. Next  element [ 5][ 5] = 45
35. Next  element [ 6][ 6] = 54
36. Next  element [ 7][ 7] = 63
37. Next  element [ 7][ 6] = 62
38. Next  element [ 6][ 5] = 53
39. Next  element [ 5][ 4] = 44
40. Next  element [ 4][ 3] = 35
41. Next  element [ 3][ 2] = 26
42. Next  element [ 2][ 1] = 17
43. Next  element [ 1][ 0] =  8
44. Next  element [ 2][ 0] = 16
45. Next  element [ 3][ 1] = 25
46. Next  element [ 4][ 2] = 34
47. Next  element [ 5][ 3] = 43
48. Next  element [ 6][ 4] = 52
49. Next  element [ 7][ 5] = 61
50. Next  element [ 7][ 4] = 60
51. Next  element [ 6][ 3] = 51
52. Next  element [ 5][ 2] = 42
53. Next  element [ 4][ 1] = 33
54. Next  element [ 3][ 0] = 24
55. Next  element [ 4][ 0] = 32
56. Next  element [ 5][ 1] = 41
57. Next  element [ 6][ 2] = 50
58. Next  element [ 7][ 3] = 59
59. Next  element [ 7][ 2] = 58
60. Next  element [ 6][ 1] = 49
61. Next  element [ 5][ 0] = 40
62. Next  element [ 6][ 0] = 48
63. Next  element [ 7][ 1] = 57
64. Next  element [ 7][ 0] = 56
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olmpazwi

olmpazwi2#

如何解决编码问题？一步一个脚印。
按照图片中的路径，让我们列出前几个整数数组下标。

0, 7
0, 6
1, 7
2, 7
1, 6
0, 5
0, 4
1, 5
2, 6
3, 7

您需要列出足够多的下标来查看开发的模式。
一种可能的解决方案是在不同的数组中编写下标。不幸的是，这个解决方案会将您锁定在一个8 x 8的矩阵中。
那么，让我们编写一些代码来获得矩阵的前几个值。这不是什么好代码。我们还在想办法。

import java.util.Arrays;

public class ArrayWalk {

    public static void main(String args[]) {
        int height = 8;
        int width = 8;

        ArrayWalk aw = new ArrayWalk();
        int[][] myArray = aw.createArray(height, width);
        int[] values = aw.walkArray(myArray);

        System.out.println(Arrays.toString(values));
    }

    private int[][] createArray(int height, int width) {
        int[][] myArray = new int[height][width];

        int start = 0;

        for (int h = 0; h < height; h++) {
            for (int w = 0; w < width; w++) {
                myArray[h][w] = start;
                start++;
            }
        }

        return myArray;
    }

    private int[] walkArray(int[][] myArray) {
        int height = myArray.length;
        int width = myArray[0].length;
        int length = height * width;
        int[] values = new int[length];
        int index = 0;

        int h = 0;
        int w = width - 1;
        values[index++] = myArray[h][w];

        w--;
        values[index++] = myArray[h][w];

        h++;
        w++;
        values[index++] = myArray[h][w];

        h++;
        values[index++] = myArray[h][w];

        h--;
        w--;
        values[index++] = myArray[h][w];

        h--;
        w--;
        values[index++] = myArray[h][w];

        w--;
        values[index++] = myArray[h][w];

        h++;
        w++;
        values[index++] = myArray[h][w];

        h++;
        w++;
        values[index++] = myArray[h][w];

        h++;
        w++;
        values[index++] = myArray[h][w];

        h++;
        values[index++] = myArray[h][w];

        h--;
        w--;
        values[index++] = myArray[h][w];

        h--;
        w--;
        values[index++] = myArray[h][w];

        h--;
        w--;
        values[index++] = myArray[h][w];

        h--;
        w--;
        values[index++] = myArray[h][w];

        return values;
    }

}

如您所见，我们已经确定需要设置矩阵的宽度和高度，并且需要返回一个整数数组来保存矩阵值。
到目前为止，还不错。
更重要的是，我们看到一种模式正在发展。让我们看看下标。

w--

h++
w++   (once)

h++

h--
w--   (twice)

这个模式重复，除了双下标重复一次、两次、三次，最多七次（宽度为1）。然后双下标重复6、5、4等次。
上排和下排总是向左移动。第一列和最后一列总是下移。
现在，在这一点上，我不确定我刚才说的是否适用于矩形矩阵。我很确定它适用于方阵。
让我们用所获得的知识编写一个助手方法。此模式是工厂模式。

private Dimension[] createIncrements() {
    Dimension[] increments = new Dimension[4];
    increments[0] = new Dimension(-1, 0);
    increments[1] = new Dimension(1, 1);
    increments[2] = new Dimension(0, 1);
    increments[3] = new Dimension(-1, -1);
    return increments;
}

一个java.awt.dimension包含一个宽度和一个高度。因此，我们定义了在代码模式中看到的四个增量。然后我们可以循环这些增量。诀窍是跟踪我们需要使用第一个和第三个（基于零的）增量增加多少次。我们得从1数到7，再倒数到1。
我已经试验了好几个小时了。这是一个很难解决的问题。我明天就去接我下班的地方。
我希望我给你的描述对你有帮助。
编辑补充：我不确定我会在其他答案中提出算法。我最终所做的就是编写一些代码来测试不同的数组大小。
这是一个测试的结果。

-------------------
|   0 |   1 |   2 |
-------------------
|   3 |   4 |   5 |
-------------------
|   6 |   7 |   8 |
-------------------

[2, 1, 5, 8, 4, 0, 3, 7, 6]

另一个测试

-------------------------------
|   0 |   1 |   2 |   3 |   4 |
-------------------------------
|   5 |   6 |   7 |   8 |   9 |
-------------------------------

[4, 3, 9, 8, 2, 1, 7, 6, 0, 5]

最后，对图像进行8x8测试。

-------------------------------------------------
|   0 |   1 |   2 |   3 |   4 |   5 |   6 |   7 |
-------------------------------------------------
|   8 |   9 |  10 |  11 |  12 |  13 |  14 |  15 |
-------------------------------------------------
|  16 |  17 |  18 |  19 |  20 |  21 |  22 |  23 |
-------------------------------------------------
|  24 |  25 |  26 |  27 |  28 |  29 |  30 |  31 |
-------------------------------------------------
|  32 |  33 |  34 |  35 |  36 |  37 |  38 |  39 |
-------------------------------------------------
|  40 |  41 |  42 |  43 |  44 |  45 |  46 |  47 |
-------------------------------------------------
|  48 |  49 |  50 |  51 |  52 |  53 |  54 |  55 |
-------------------------------------------------
|  56 |  57 |  58 |  59 |  60 |  61 |  62 |  63 |
-------------------------------------------------

[7, 6, 15, 23, 14, 5, 4, 13, 22, 31, 39, 30, 21, 12, 3, 2, 11, 20, 29, 38, 
47, 55, 46, 37, 28, 19, 10, 1, 0, 9, 18, 27, 36, 45, 54, 63, 62, 53, 44, 35, 
26, 17, 8, 16, 25, 34, 43, 52, 61, 60, 51, 42, 33, 24, 32, 41, 50, 59, 58, 
49, 40, 48, 57, 56]

这是密码。

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class ArrayWalk {

    public static void main(String args[]) {
        int height = 8;
        int width = 8;

        ArrayWalk aw = new ArrayWalk();
        int[][] myArray = aw.createArray(height, width);
        System.out.println(aw.printArray(myArray));

        int[] values = aw.walkArray(myArray);
        System.out.println(Arrays.toString(values));
    }

    private int[][] createArray(int height, int width) {
        int[][] myArray = new int[height][width];

        int start = 0;

        for (int h = 0; h < height; h++) {
            for (int w = 0; w < width; w++) {
                myArray[h][w] = start;
                start++;
            }
        }

        return myArray;
    }

    private int[] walkArray(int[][] myArray) {
        int totalRows = myArray.length;
        int totalCols = myArray[0].length;

        List<Integer> res = new ArrayList<>(totalRows * totalCols);
        List<Integer> diagonal = new ArrayList<>(
                Math.max(totalRows, totalCols));

        boolean reverseOrder = true;

        for (int col = totalCols - 1; col >= 0; col--) {
            for (int row = 0; row < totalRows && col + row < totalCols; row++) {
                diagonal.add(myArray[row][col + row]);
            }

            if (reverseOrder) {
                Collections.reverse(diagonal);
            }

            res.addAll(diagonal);
            reverseOrder = !reverseOrder;
            diagonal.clear();
        }

        for (int row = 1; row < totalRows; row++) {
            for (int col = 0; col < totalCols && col + row < totalRows; col++) {
                diagonal.add(myArray[col + row][col]);
            }

            if (reverseOrder) {
                Collections.reverse(diagonal);
            }

            res.addAll(diagonal);
            reverseOrder = !reverseOrder;
            diagonal.clear();
        }

        int[] output = new int[res.size()];
        for (int i = 0; i < res.size(); i++) {
            output[i] = res.get(i);
        }
        return output;
    }

    private String printArray(int[][] myArray) {
        String output = "";
        for (int h = 0; h < myArray.length; h++) {
            output += printDashes(myArray[h].length) + "\n";
            output += printLine(myArray[h]) + "\n";
        }
        output += printDashes(myArray[0].length) + "\n";
        return output;
    }

    private String printDashes(int width) {
        int count = width * 6 + 1;
        String output = "";

        for (int i = 0; i < count; i++) {
            output += "-";
        }

        return output;
    }

    private String printLine(int[] array) {
        String output = "|";

        for (int i = 0; i < array.length; i++) {
            String value = String.format("%3d", array[i]);
            output += " " + value + " |";
        }

        return output;
    }

}
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snz8szmq

snz8szmq3#

public static List<Integer> readMatrix(int[][] matrix) {
    int totalRows = matrix.length;
    int totalCols = matrix[0].length;

    List<Integer> res = new ArrayList<>(totalRows * totalCols);
    List<Integer> diagonal = new ArrayList<>(Math.max(totalRows, totalCols));

    boolean reverseOrder = true;

    for (int col = totalCols - 1; col >= 0; col--) {
        for (int row = 0; row < totalRows && col + row < totalCols; row++)
            diagonal.add(matrix[row][col + row]);

        if (reverseOrder)
            Collections.reverse(diagonal);

        res.addAll(diagonal);
        reverseOrder = !reverseOrder;
        diagonal.clear();
    }

    for (int row = 1; row < totalRows; row++) {
        for (int col = 0; col < totalCols && col + row < totalRows; col++)
            diagonal.add(matrix[col + row][col]);

        if (reverseOrder)
            Collections.reverse(diagonal);

        res.addAll(diagonal);
        reverseOrder = !reverseOrder;
        diagonal.clear();
    }

    return res;
}
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