SpiralMartix.java

class SpiralMartix {
    public List < Integer > spiralOrder(int[][] matrix) {
        List list = new ArrayList();
        if (matrix.length == 0)
            return list;
        int r1 = 0, r2 = matrix.length - 1;
        int c1 = 0, c2 = matrix[0].length - 1;
        while (r1 <= r2 && c1 <= c2) {
            for (int c = c1; c <= c2; c++) list.add(matrix[r1][c]);
            for (int r = r1 + 1; r <= r2; r++) list.add(matrix[r][c2]);
            if (r1 < r2 && c1 < c2) {
                for (int c = c2 - 1; c > c1; c--) list.add(matrix[r2][c]);
                for (int r = r2; r > r1; r--) list.add(matrix[r][c1]);
            }
            r1++;
            r2--;
            c1++;
            c2--;
        }
        return list;
    }
}