力扣：54. 螺旋矩阵

import java.util.ArrayList;
import java.util.List;

/**
 * @author xnl
 * @Description:
 * @date: 2022/7/3   22:38
 */
public class Solution {
    public static void main(String[] args) {
        Solution solution = new Solution();
        int[][] matrix = {{1,2,3},{4,5,6},{7,8,9}};
        System.out.println(solution.spiralOrder(matrix).toString());
    }

    public List<Integer> spiralOrder(int[][] matrix) {
        List<Integer>  res = new ArrayList<>();
        int m = matrix.length, n = matrix[0].length;
        int[][] directions = {{0 ,1}, {1, 0}, {0, -1}, {- 1, 0}};
        boolean[][] vis = new boolean[m][n];
        int direction = 0;
        int row = 0;
        int col = 0;
        for(int i = 0; i < m * n; i++ ){
            res.add(matrix[row][col]);
            vis[row][col] = true;
            int next_row  = row + directions[direction][0];
            int next_col  = col + directions[direction][1];
            if (next_col < 0 || next_col >= n || next_row >= m || vis[next_row][next_col] ){
                direction = (direction + 1) % 4;
            }
            row = row + directions[direction][0];
            col = col + directions[direction][1];
        }
        return res;
    }
}