spiral_matrix.py

class Solution:
    def spiralOrder(self, matrix):
        n, m = len(matrix), len(matrix[0])
        i, j = 0, 0
        delta = (0, 1)
        direction_map = {(0, 1): (1, 0), (1, 0): (0, -1), (0, -1): (-1, 0), (-1, 0): (0, 1)}
        spiral = [matrix[i][j]]
        matrix[i][j] = None
        while len(spiral) < n*m:
            next_i, next_j = i+delta[0], j+delta[1]
            if next_i < 0 or next_i == n or next_j < 0 or next_j == m or matrix[next_i][next_j] is None:
                delta = direction_map[delta]
            else:
                i, j = next_i, next_j
                spiral.append(matrix[i][j])
                matrix[i][j] = None
        return spiral