Shift 2D Grid Python Solution with Tests

lcpy gen -n 1260   # by problem number
lcpy gen -s shift_2d_grid   # by problem name

Input: grid = [[1,2,3],[4,5,6],[7,8,9]], k = 1
Output: [[9,1,2],[3,4,5],[6,7,8]]

Input: grid = [[3,8,1,9],[19,7,2,5],[4,6,11,10],[12,0,21,13]], k = 4
Output: [[12,0,21,13],[3,8,1,9],[19,7,2,5],[4,6,11,10]]

Input: grid = [[1,2,3],[4,5,6],[7,8,9]], k = 9
Output: [[1,2,3],[4,5,6],[7,8,9]]

class Solution:
    def shift_grid(self, grid: list[list[int]], k: int) -> list[list[int]]:
        m, n = len(grid), len(grid[0])
        total = m * n
        k %= total
        flat = [grid[i][j] for i in range(m) for j in range(n)]
        flat = flat[-k:] + flat[:-k] if k else flat
        return [flat[i * n : (i + 1) * n] for i in range(m)]