[leetcode]Spiral Matrix II @ Python

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

题意：

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

For example,
Given n = 3,

You should return the following matrix:

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

解题思路：和上题差不多的思路。

代码：

class Solution:
    # @return a list of lists of integer
    def generateMatrix(self, n):
        if n == 0: return []
        matrix = [[0 for i in range(n)] for j in range(n)]
        up = 0; down = len(matrix)-1
        left = 0; right = len(matrix[0])-1
        direct = 0; count = 0
        while True:
            if direct == 0:
                for i in range(left, right+1):
                    count += 1; matrix[up][i] = count
                up += 1
            if direct == 1:
                for i in range(up, down+1):
                    count += 1; matrix[i][right] = count
                right -= 1
            if direct == 2:
                for i in range(right, left-1, -1):
                    count += 1; matrix[down][i] = count
                down -= 1
            if direct == 3:
                for i in range(down, up-1, -1):
                    count += 1; matrix[i][left] = count
                left += 1
            if count == n*n: return matrix
            direct = (direct+1) % 4