[leetcode]Spiral Matrix @ Python

原题地址：https://oj.leetcode.com/problems/spiral-matrix/

题意：

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

For example,
Given the following matrix:

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

You should return [1,2,3,6,9,8,7,4,5].

解题思路：来段精巧的代码。

代码：

class Solution:
    # @param matrix, a list of lists of integers
    # @return a list of integers
    def spiralOrder(self, matrix):
        if matrix == []: return []
        up = 0; left = 0
        down = len(matrix)-1
        right = len(matrix[0])-1
        direct = 0  # 0: go right   1: go down  2: go left  3: go up
        res = []
        while True:
            if direct == 0:
                for i in range(left, right+1):
                    res.append(matrix[up][i])
                up += 1
            if direct == 1:
                for i in range(up, down+1):
                    res.append(matrix[i][right])
                right -= 1
            if direct == 2:
                for i in range(right, left-1, -1):
                    res.append(matrix[down][i])
                down -= 1
            if direct == 3:
                for i in range(down, up-1, -1):
                    res.append(matrix[i][left])
                left += 1
            if up > down or left > right: return res
            direct = (direct+1) % 4