【LeetCode with Python】 54. Spiral Matrix

题目

原题页面:https://oj.leetcode.com/problems/spiral-matrix/
本文地址:http://leetcode.xnerv.wang/spiral-matrix/
题目类型:Array
难度评价:Medium
类似题目:(M) Spiral Matrix II

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:
[<br/> [ 1, 2, 3 ],<br/> [ 4, 5, 6 ],<br/> [ 7, 8, 9 ]<br/> ]
You should return [1,2,3,6,9,8,7,4,5].


分析

还是一道下标计算的题目,用两重嵌套for循环,以螺旋状的方式遍历二维数组。


代码

class Solution:
    # @param matrix, a list of lists of integers
    # @return a list of integers
    def spiralOrder(self, matrix):

        m = len(matrix)
        if 0 == m:
            return [ ]
        n = len(matrix[0])
        if 0 == n:
            return [ ]
        arr = [ ]

        round = (min(m, n) + 1) / 2
        for x in range(0, round):
            for y in range(x, n - x):
                arr.append(matrix[x][y])
            for y in range(x + 1, m - x - 1):
                arr.append(matrix[y][n - x - 1])
            if m - 2 * x > 1:  ###
                for y in range(n - x - 1, x - 1, -1):
                    arr.append(matrix[m - x - 1][y])
            if n - 2 * x > 1:      ###
                for y in range(m - x - 2, x, -1):   ###
                    arr.append(matrix[y][x])
        return arr

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