867. 转置矩阵 - H1S97X's Blog

Problem#

给你一个二维整数数组 matrix，返回 matrix 的 转置矩阵。

矩阵的转置是指将矩阵的行列互换，即 result[j][i] = matrix[i][j]。

https://leetcode.cn/problems/transpose-matrix/description/

示例 1：

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

示例 2：

输入：matrix = [[1,2,3],[4,5,6]] 输出：[[1,4],[2,5],[3,6]]

约束：

1 <= matrix.length <= 1000
1 <= matrix[0].length <= 1000

思路#

转置后行列互换，新矩阵的列数等于原矩阵的行数，新矩阵的行数等于原矩阵的列数。

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class Solution:
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    def transpose(self, matrix: list[list[int]]) -> list[list[int]]:
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        rows, cols = len(matrix), len(matrix[0])
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        result = [[0] * rows for _ in range(cols)]
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        for i in range(rows):
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            for j in range(cols):
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                result[j][i] = matrix[i][j]
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        return result

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import unittest
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class TestTranspose(unittest.TestCase):
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    def setUp(self):
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        self.solution = Solution()
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    def test_square(self):
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        self.assertEqual(self.solution.transpose([[1, 2, 3], [4, 5, 6], [7, 8, 9]]),
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                         [[1, 4, 7], [2, 5, 8], [3, 6, 9]])
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    def test_rectangular(self):
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        self.assertEqual(self.solution.transpose([[1, 2, 3], [4, 5, 6]]),
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                         [[1, 4], [2, 5], [3, 6]])
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    def test_single(self):
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        self.assertEqual(self.solution.transpose([[1]]), [[1]])
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if __name__ == '__main__':
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    unittest.main()