import random


def make2D_grid_random_fill(rows, cols):
    """Returns a 2d grid filled with RANDOM zeros and ones"""
    grid = []

    for x in range(0, cols):
        grid.append([])
        for y in range(0, rows):
            if random.randint(0, 2) == 0:  # 33% change of filling square
                grid[x].append(1)
            else:
                grid[x].append(0)

    return grid