技術標籤：leetcode

題目描述

輸入一個矩陣，按照從外向裡以順時針的順序依次打印出每一個數字。

示例 1：

輸入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
輸出：[1,2,3,6,9,8,7,4,5]
示例 2：

輸入：matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
輸出：[1,2,3,4,8,12,11,10,9,5,6,7]

限制：

0 <= matrix.length <= 100
0 <= matrix[i].length <= 100

按層來迴圈

class Solution {
    public
 
 int[] spiralOrder(int[][] matrix) {
        if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {
            return new int[0];
        }
        int rows = matrix.length, columns = matrix[0].length;
        int[] res = new int[rows*columns];
        int index =0;
        int left=0,right=
 
columns-1,top=0,bottom=rows-1;

        while(left<=right && top<=bottom){
            for(int column=left;column<=right;column++) res[index++] = matrix[top][column];
            for(int row=top+1;row<=bottom;row++) res[index++] = matrix[row][right];
            
            if(left<
 
right && top<bottom){
                for(int column=right-1;column>left;column--) res[index++] = matrix[bottom][column];
                for(int row=bottom;row>top;row--) res[index++] = matrix[row][left];
            }
            left++;right--;top++;bottom--;            
        }
        return res;
    }
}