我也曾经对那种力量一无所知！论算法的重要性

输入:
[
 [ 1, 2, 3 ],
 [ 4, 5, 6 ],
 [ 7, 8, 9 ]
]
输出: [1,2,3,6,9,8,7,4,5]

输入:
[
  [1, 2, 3, 4],
  [5, 6, 7, 8],
  [9,10,11,12]
]
输出: [1,2,3,4,8,12,11,10,9,5,6,7]

# solution 1
class Solution:
  def spiralOrder(self, matrix):
  """
  :type matrix: List[List[int]]
  :rtype: List[int]
  """
  if matrix == [] : return []
  res = []
  maxUp = maxLeft = 0
  maxDown = len(matrix) - 1
  maxRight = len(matrix[0]) - 1
  direction = 0 # go right, 1 go down, 2 go left, 3 up 
  while True:
      if direction == 0: 
          for i in range(maxLeft, maxRight+1):
              res.append(matrix[maxUp][i])
          maxUp += 1
      elif direction == 1:        # go down
          for i in range(maxUp, maxDown+1):
           		 res.append(matrix[i][maxRight])
          maxRight -= 1
      elif direction == 2:         # go left
          for i in reversed(range(maxLeft, maxRight+1)):
               res.append(matrix[maxDown][i])
          maxDown -= 1
      else:   # go up
          for i in reversed(range(maxUp, maxDown+1)):
              res.append(matrix[i][maxLeft])
          maxLeft += 1
      if maxUp > maxDown or maxLeft > maxRight:
          return res 
      direction = (direction + 1) % 4      

# solution 2
class Solution:
    def spiralOrder(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: List[int]
        """
        
 				if len(matrix) == 0: return []
        
        left = 0
        up = 0
        down = len(matrix) - 1
        right = len(matrix[0]) - 1
        # 0 -> right, 1 -> down, 2 -> left, 3 -> up
        direction = 0
        # start location
        x, y = 0, 0
        res = []
        while True:
            if left > right or up > down:
                return res 
            if direction == 0:
                while y <= right:
                    res.append(matrix[up][y])
                    y += 1
                up += 1
                x = up 
                direction = 1
                continue
            if direction == 1:
                while x <= down:
                    res.append(matrix[x][right])
                    x += 1
                right -= 1
                y = right
                direction = 2
                continue 
            if direction == 2:
                while y >= left:
                    res.append(matrix[down][y])
                    y -= 1
                down -= 1
                x =down
                direction = 3
                continue
            if direction == 3:
                while x >= up:
                    res.append(matrix[x][left])
                    x -= 1
                left += 1
                y = left
                direction = 0
                continue 

# solution 3
# 一行代码搞定
lass Solution:
    def spiralOrder(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: List[int]
        """
        return matrix and list(matrix.pop(0)) + self.spiralOrder(list(zip(*matrix))[::-1])