剑指 Offer 29. 顺时针打印矩阵

class Solution {
    public int[] spiralOrder(int[][] matrix) {
        if (matrix==null || matrix.length==0)
            return new int[0];
        int i = 0;
        int j = 0;
        int[][] index = new int[matrix.length][matrix[0].length];
        int[] arr = new int[matrix.length * matrix[0].length];
        int ind = 0;
        while (true) {
            int flag = 0;
            while (j < matrix[0].length && index[i][j] == 0) {
                index[i][j] = 1;
                arr[ind++] = (matrix[i][j++]);
                flag = 1;
            }
            j--;
            i++;
            while (i < matrix.length && index[i][j] == 0) {
                index[i][j] = 1;
                arr[ind++] = (matrix[i++][j]);
                if (flag == 1)
                    flag = 2;
            }
            i--;
            j--;
            while (j >= 0 && index[i][j] == 0) {
                index[i][j] = 1;
                arr[ind++] = (matrix[i][j--]);
                if (flag == 2)
                    flag = 3;
            }
            j++;
            i--;
            while (i >= 0 && index[i][j] == 0) {
                index[i][j] = 1;
                arr[ind++] = (matrix[i--][j]);
                if (flag == 3)
                    flag = 4;
            }
            i++;
            j++;
            if (flag != 4)
                break;

        }
        return arr;
    }
}