无聊系列 - 螺旋矩阵算法实现

前段时间无意中看到一个螺旋矩阵的面试题，于是网上搜了下，发现有两种螺旋矩阵：

1. 百度百科上描述的这种：https://baike.baidu.com/item/%E8%9E%BA%E6%97%8B%E7%9F%A9%E9%98%B5/3528521?fr=aladdin

2. leet code上的螺旋矩阵输出。

先贴百科上的：

public class SpiralMatrix {
    public static void main(String[] args) {
        int n = 11, m = 7;

        int[][] elements = new int[n][m];

        int temp = 0;
        int row = 0, col = 0;
        int maxN = n, maxM = m;

        while (temp < n * m) {

            int tempRow = row, tempCol = col;
            // top
            for (; tempCol < maxM; tempCol++) {
                temp++;
                elements[tempRow][tempCol] = temp;
            }

            if (temp >= n * m)
                break;

            // right
            tempCol--;
            for (tempRow = tempRow + 1; tempRow < maxN; tempRow++) {
                temp++;
                elements[tempRow][tempCol] = temp;
            }
            if (temp >= n * m)
                break;
            tempRow--;

            // bottom
            tempCol--;
            for (; tempCol >= m - maxM; tempCol--) {
                temp++;
                elements[tempRow][tempCol] = temp;
            }
            if (temp >= n * m)
                break;
            // left
            tempCol++;
            for (tempRow = tempRow - 1; tempRow > n - maxN; tempRow--) {
                temp++;
                elements[tempRow][tempCol] = temp;
            }

            if (temp >= n * m)
                break;

            row++;
            col++;

            maxM--;
            maxN--;
        }

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (elements[i][j] < 10)
                    System.out.print("0");

                System.out.print(elements[i][j]);
                System.out.print("  ");
            }
            System.out.println();
        }
    }
}

【力扣算法】54-螺旋矩阵：

public static List<Integer> spiralOrder(int[][] matrix) {
        List<Integer> result = new LinkedList<>();
        
        if (matrix.length == 0)
            return result;        

        int maxRow = matrix.length;
        int maxCol = matrix[0].length;

        int total = maxRow * maxCol;

        // 统计已经读取了多少个数字
        int num = 0;

        int row = 0, col = 0;

        while (num < total) {
            int tempRow = row, tempCol = col;
            // top
            for (; tempCol < maxCol; tempCol++) {
                num++;
                result.add(matrix[tempRow][tempCol]);
            }
            // 读取的个数达到矩阵元素总数，则退出循环
            if (num >= total)
                break;

            // right
            tempCol--;
            for (tempRow = tempRow + 1; tempRow < maxRow; tempRow++) {
                num++;
                result.add(matrix[tempRow][tempCol]);
            }
            tempRow--;

            if (num >= total)
                break;

            // bottom
            tempCol--;
            for (; tempCol >= col; tempCol--) {
                num++;
                result.add(matrix[tempRow][tempCol]);
            }
            if (num >= total)
                break;

            // left
            tempCol++;
            for (tempRow = tempRow - 1; tempRow > row; tempRow--) {
                num++;
                result.add(matrix[tempRow][tempCol]);
            }

            if (num >= total)
                break;

            row++;
            col++;

            maxCol--;
            maxRow--;
        }

        return result;
    }

    public static void main(String[] args) {
        int[][] matrix = new int[][] { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };

        matrix = new int[][] { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 } };

        List<Integer> result = spiralOrder(matrix);

        for (Integer integer : result) {
            System.out.print(integer);
            System.out.print("  ");
        }
    }

 

 

【力扣算法】54-螺旋矩阵