def sprinkler_reaches_cell(x, y, sx, sy, r):
    """
    Return whether a cell is within the radius of the sprinkler.

    x:  column index of cell
    y:  row index of cell
    sx:  column index of sprinkler
    sy:  row index of sprinkler
    r:  sprinkler radius
    """
    dx = sx - x
    dy = sy - y
    return math.sqrt(dx ** 2 + dy ** 2) <= r