题解 | #螺旋矩阵#

import java.util.ArrayList;
public class Solution {
   public ArrayList<Integer> spiralOrder(int[][] matrix) {
        ArrayList<Integer> res = new ArrayList<>();
        if (matrix.length == 0) {
            return res;
        }
        //定义边界
        int low = 0, high = matrix.length - 1, left = 0, right = matrix[0].length - 1;
        //定义游标
        while (left <= right && low <= high) {//直到左右边界 和 上下边界重合为止
            for (int i = left; i <= right; i++) {
                res.add(matrix[low][i]);
            }
            low++;
            if (low>high){
                break;
            }
            for (int i = low; i <= high; i++) {
                res.add(matrix[i][right]);
            }
            right--;
            if(left>right){
                break;
            }
            for ( int i = right; i >= left; i--) {
                res.add(matrix[high][i]);
            }
            high--;
            if(low>high){
                break;
            }
            for (int i = high; i >= low; i--) {
                res.add(matrix[i][left]);
            }
            left++;
            if(left>right){
                break;
            }
        }
        return res;
    }
}