from decimal import Decimal as dec

def light_through_glass(panes, iterations):
    rays = [[dec(0)]*(panes+1), [dec(100)]+[dec(0)]*(panes)]
    out = [dec(0)]*2
    percent = 10
    print('0%'),
    for i in range(iterations):
        # Graphic bling-bling
        if float(i)/float(iterations)*100 >= percent:
            print(str(percent)+'%'),
            percent += 10
        newrays = [[dec(0)]*(panes+1),[dec(0)]*(panes+1)]
        for d in (0, 1):
            for n,r in enumerate(rays[d]):
                if r == 0:
                    continue
                if n == panes*d:
                    out[d] += r
                else:
                    newrays[abs(d-1)][n] += r/10
                    newrays[d][n-1+d*2] += r * dec('0.9')
        rays = newrays
    return out

if __name__ == '__main__':
    panes = 50
    iterations = 200
    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)))