题解 | #牧场边界巡游#

class Solution:
    def spiralTravelCounterClockwise(self , matrix: List[List[int]]) -> List[int]:
        # write code here
        if not matrix:
            return []

        m, n = len(matrix), len(matrix[0])
        res = []

        def spiral(start_row, end_row, start_col, end_col):
            if start_row > end_row or start_col > end_col:
                return
            
            # 遍历左侧的列
            for i in range(start_row, end_row + 1):
                res.append(matrix[i][start_col])

            # 遍历下方的行
            for j in range(start_col + 1, end_col+1):
                res.append(matrix[end_row][j])

            # 遍历右侧的列
            if start_col < end_col:
                for i in range(end_row-1, start_row-1, -1):
                    res.append(matrix[i][end_col])

            # 遍历上方的行
            if start_row < end_row:
                for j in range(end_col-1,start_col,-1):
                    res.append(matrix[start_row][j])

            # 递归处理内部的子矩阵
            spiral(start_row + 1, end_row - 1, start_col + 1, end_col - 1)

        spiral(0, m - 1, 0, n - 1)
        return res