剑指 Offer 29. 顺时针打印矩阵

package leetcode;


public class offer_29 {
    public int[] spiralOrder(int[][] matrix) {
        //空数组
        if(matrix==null||matrix.length==0||matrix[0].length==0) {return new int[0];}
        int height=matrix.length;
        int width=matrix[0].length;
        int arr[]=new int[height*width];
        int count=0;
        int i=0;
        int j=0;
        //上下左右边界
        int up=0;
        int down=height-1;
        int left=0;
        int right=width-1;
        while(count<arr.length) {
            //上边界
            for(j=left;count<arr.length&&j<=right;j++) {
                arr[count]=matrix[up][j];
                count=count+1;
            }
            //更新上边界
            up=up+1;
            //右边界
            for(i=up;count<arr.length&&i<=down;i++) {
                arr[count]=matrix[i][right];
                count++;
            }
            //更新右边界
            right=right-1;
            //下边界
            for(j=right;count<arr.length&&j>=left;j--) {
                arr[count]=matrix[down][j];
                count++;
            }
            //更新下边界
            down=down-1;
            //左边界
            for(i=down;count<arr.length&&i>=up;i--) {
                arr[count]=matrix[i][left];
                count++;
            }
            //更新左边界
            left=left+1;
        }
        for (int k : arr) {
            System.out.println(k);
        }
        return arr;
        
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        offer_29 off=new offer_29();
        int nums[][]= {{1,2,3,4},{5,6,7,8},{9,10,11,12}};
        off.spiralOrder(nums);
    }

}