Leetcode exercise (Python): Array class: Question 54: Given a matrix with mxn elements (m rows, n columns), return all the elements in the matrix in a clockwise spiral order.

topic:

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

Ideas:

Use two pointers and control the boundary.

program:

class Solution:

    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:

        row = len(matrix)

        if row <= 0:

            return []

        column = len(matrix[0])

        result = []

        row_begin = 0

        row_end = row - 1

        column_begin = 0

        column_end = column - 1

        while row_begin <= row_end and column_begin <= column_end:

            for index1 in range(column_begin, column_end + 1):

                result.append(matrix[row_begin][index1])

            row_begin += 1

            

            for index2 in range(row_begin, row_end + 1):

                result.append(matrix[index2][column_end])

            column_end -= 1

            for index1 in range(column_end, column_begin - 1, -1):

                if row_end >= row_begin:

                    result.append(matrix[row_end][index1])

            row_end -= 1

            for index2 in range(row_end, row_begin - 1, -1):

                if column_end >= column_begin:

                    result.append(matrix[index2][column_begin])

            column_begin += 1

        

        return result