Transpose a Grade Matrix

Hard ⏱ 18 min 39% acceptance ★★★★★ 4.9

Grades are stored per-student as rows; analysts want them per-subject as columns. Write transpose(matrix) for a rectangular list-of-lists using nested comprehensions only — no zip.

Examples

Example 1

Input

transpose([[1, 2, 3], [4, 5, 6]])

Output

[[1, 4], [2, 5], [3, 6]]

Explanation

Rows become columns.

Constraints

No zip, no numpy.
Assume a non-empty rectangular matrix.

Topics

List Comprehensionsnested comprehension

Companies

GoogleMicrosoft

Hints

Hint 1

The outer comprehension iterates over column indices.

Hint 2

[[row[i] for row in matrix] for i in range(len(matrix[0]))].

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