顺时针打印矩阵 - xiewenfeng/test GitHub Wiki

例如：如果输入如下矩阵：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

则依次打印出数字1, 2, 3, 4, 8, 12, 16, 15, 14, 13, 9, 5, 6, 7, 11, 10。 思路： 矩阵打印都是从外圈到内圈依次打印，假设矩阵是rows行*columns列，我们矩阵的宽度为columns, 高度为rows,我们取左上角开始的坐标为startX, startY，就像剥洋葱一样一圈一圈往里，每次剥掉一圈，矩阵至少会减少两行两列，每剥掉一圈，我们将startX、startY各加1，这样我们可以得出最多可以进行剥掉层次数startX < columns/2; startY < rows/2;

private void printMatrix(int[][] arrayRect, int columns, int rows) {
        if (arrayRect == null || columns <= 0 || rows <= 0) {
            return;
        }
        int startX = 0, startY = 0;
        int endX = 0, endY = 0;
        while(columns > startX * 2 && columns > startY * 2) {
            printMatrixCircle(arrayRect, endY, endX, startX, startY);
            ++startX;
            --rows;
            --columns;
            ++startY;
        }
    }



    private void printMatrixCircle(int[][] matrix, int columns, int rows, int startX, int startY) {
        for (int i = startX; i < columns; i++) {
            System.out.print(matrix[i][startY]);
        }
        System.out.println("");
        for (int i = startY + 1; i < rows; i++) {
            System.out.print(matrix[columns - 1][i]);
        }
        System.out.println("");
        for (int i = columns - 2; i >= startX; i--) {
            System.out.print(matrix[i][rows - 1]);
        }
        System.out.println("");
        for (int i = rows - 2; i > startY; i--) {
            System.out.print(matrix[startX][i]);
        }
        System.out.println("");
    }