题解 | #java螺旋矩阵#

public final class SpiralMatrix {
    /**
     * @Description
     * @Author fucheng
     * @Date 2021-9-9 15:45
     * @Param []
     * @return int[][]
     */
    private int[][] construct(int h, int w) {
        int[][] arr = new int[h][w];
        int height = arr.length;
        int weight = 0;
        int temp = 1;
        System.err.println("arr.length=" + height);
        for (int i = 0; i < height; ++i) {
            if (weight == 0) weight = arr[i].length;
            for (int j = 0; j < weight; ++j) {
                arr[i][j] = temp;
                ++temp;
            }
        }
        return arr;
    }

    /**
     * @Description
     * @Author fucheng
     * @Date 2021-9-9 15:45
     * @Param [matrix]
     * @return java.util.List<java.lang.Integer>
     */
    public ArrayList<Integer> spiralOrder1(int[][] matrix) {
        int height = matrix.length;
        if (height == 0) return new ArrayList<>(0);

        int weight = matrix[0].length;
        int size = weight * height;
        ArrayList<Integer> list = new ArrayList<>(size);
        int max_h_index = height - 1;
        int max_w_index = weight - 1;
        int index1 = 0, index2 = 0, index3 = 0, index4 = 0;
        while (list.size() < size) {
            // 从左往右
            for (int j = index1; j <= max_w_index - index2; ++j) {
                list.add(matrix[index1][j]);
            }
            ++index1;
            if (list.size() == size) return list;

            //右侧 从上到下
            for (int j = index1; j <= max_h_index - index2; ++j) {
                list.add(matrix[j][max_w_index - index2]);
            }
            ++index2;
            if (list.size() == size) return list;

            //下侧从右到左
            for (int j = max_w_index - index2; j >= index3; --j) {
                list.add(matrix[max_h_index - index3][j]);
            }
            ++index3;
            if (list.size() == size) return list;

            //右侧从下到上
            for (int j = max_h_index - index3; j > index4; --j) {
                list.add(matrix[j][index4]);
            }
            ++index4;
            if (list.size() == size) return list;
        }
        return list;
    }

    /**
     * @Description
     * @Author fucheng
     * @Date 2021-9-10 15:35
     * @Param [matrix]
     * @return java.util.ArrayList<java.lang.Integer>
     */
    public ArrayList<Integer> spiralOrder(int[][] matrix) {
        int height = matrix.length;
        if (height == 0) return new ArrayList<>(0);
        int weight = matrix[0].length;
        int size = weight * height;
        ArrayList<Integer> list = new ArrayList<>(size);

        int top = 0, bottom = height - 1, left = 0, right = weight - 1;
        while (top <= bottom && left <= right) {
            // 顶部:左 -> 右, 列变,行不变
            for (int i = left; i <= right; i++) {
                list.add(matrix[top][i]);
            }
            ++top;

            // 右侧:上 -> 下, 行变,列不变
            for (int i = top; i <= bottom; i++) {
                list.add(matrix[i][right]);
            }
            --right;

            // 底部:右 -> 左, 列变,行不变
            for (int i = right; i >= left && top <= bottom; i--) {
                list.add(matrix[bottom][i]);
            }
            --bottom;

            // 左侧: 下 -> 上, 行变,列不变
            for (int i = bottom; i >= top && left <= right; i--) {
                list.add(matrix[i][left]);
            }
            ++left;
        }
        return list;
    }

    public static void main(String[] args) {
        SpiralMatrix matrix = new SpiralMatrix();
        // System.err.println(matrix.spiralOrder(matrix.construct(3, 4)));
        // System.err.println(matrix.spiralOrder(matrix.construct(4, 3)));
        //System.err.println(matrix.spiralOrder(matrix.construct(5, 6)));
        System.err.println(matrix.spiralOrder(matrix.construct(3, 1)));
    }
}