[LeetCode]54 螺旋矩阵

题目描述

给定一个包含 m x n 个元素的矩阵（m 行, n 列），请按照顺时针螺旋顺序，返回矩阵中的所有元素。

示例1:

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

示例2:

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]

代码

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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 # 0 go right, 1 go down, 2 go left, 3 up
        while True:
            if direction == 0: #go right
                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