73. Set Matrix Zeroes

class Solution:
  def setZeroes(self, matrix: List[List[int]]) -> None:

    rows = len(matrix)
    cols = len(matrix[0])

    # 1. Check first row/column for zero's
    first_row_has_zero = 0 in matrix[0]
    first_col_has_zero = 0 in list(zip(*matrix))[0]
    
    # 2. Check other cells in `matrix` and save info in the 1st row/col if cell has zero's
    for i in range(1, rows):
      for j in range(1, cols):
        if matrix[i][j] == 0:
          matrix[0][j] = 0 # 1st row
          matrix[i][0] = 0 # 1st col

    # 3. Loop again through first row/column and overwrite cells according to the data from 1st row/column
    #    except the 1st row/col
    for i in range(1, rows):
      for j in range(1, cols):
        if matrix[0][j] == 0 or matrix[i][0] == 0:
          matrix[i][j] = 0

    # Fill 0s for the 1st row if needed
    if first_row_has_zero:
      matrix[0] = [0] * cols

    # Fill 0s for the 1st col if needed
    if first_col_has_zero:
      for row in matrix:
        row[0] = 0