Level 1Exercise #13

Flatten one layer

Flatten a rectangular list of rows by exactly one nesting level.

Sample Test Cases

Example #1

Input:flatten_once([[1, 2], [3, 4]])

Output:[1,2,3,4]

Reveal Reference Solution

def flatten_once(matrix: list[list[int]]) -> list[int]:
    return [value for row in matrix for value in row]

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