from decimal import Decimal as dec

def light_through_glass(panes, iterations):
    # All simulated rays with direction [left, right]
    # Always starts with a 100% ray in the leftmost space, heading right
    # space0 pane0 space1 pane1 ... spacen panen
    rays = [[dec(0)]*(panes+1), [dec(100)]+[dec(0)]*(panes)]
    # Output, duh
    out = [dec(0)]*2 #[reflect, through]
    # Graphic blingbling gangsta yo!
    percent = 10
    print('0%'),
    for i in range(iterations):
        # Graphic bling-bling
        if float(i)/float(iterations)*100 >= percent:
            print(str(percent)+'%'),
            percent += 10
        # New nice empty array for the iterated rays
        # (when we've done stuff to them ehehe)
        # And just like rays they are 1 longer than panes _ | _ | _<--see?
        newrays = [[dec(0)]*(panes+1),[dec(0)]*(panes+1)]
        # 'd' as in direction! 0 is left, 1 is right
        for d in (0, 1):
            # parse all positions in rays[] no, MOOVE
            # n is the position among the panes, r is the strength-thingy
            for n,r in enumerate(rays[d]):
                # go frak yourself if the space is pitch black dark eh
                if r == 0:
                    continue
                # if the rays are at the end and heading away, put them
                # out of their misery (to out[], either reflect or through
                # depending on n's position)
                if n == panes*d:
                    out[d] += r
                # no we're talking yo!
                else:
                    # dump a 10%-ish ray on the same space, but reverse dir
                    newrays[abs(d-1)][n] += r/10
                    # push away a 90% ray to the next space in the ray's
                    # direction, shablam!
                    newrays[d][n-1+d*2] += r * dec('0.9')
        # dump the old crap and in with the new AHAAH
        rays = newrays
    # gtfo :*
    return out

if __name__ == '__main__':
    panes = 100
    iterations = 1000
    print('panes: {0}, iterations: {1}'.format(panes, iterations))
    data = light_through_glass(panes, iterations)
    print('\nreflect: {0}\nthrough: {1}\nloss: {2}'.format(data[0], data[1],
                                                    100-sum(data)))
# good stuff