k2.py

import sys, math
p,t,w=map(int,sys.argv[1:]) # read input
grid = [[' ']*(w+1) for i in range(0,w+1)] # prepare grid

def plot(x,y): 
    """plots point on grid"""
    grid[int(round(x))][int(round(y))]='x'

def line (x0, y0, x1, y1):
    """draw line using bresenham's line algorithm"""
    steep = abs(y1 - y0) > abs(x1 - x0)
    if steep: 
        (x0,y0,x1,y1) = (y0,x0,y1,x1)
    if x0 > x1: 
        (x0,y0,x1,y1) = (x1,y1,x0,y0)
    dx = x1 - x0
    dy = abs(y1 - y0)
    err = dx/2
    y = y0
    if y0 < y1:
        ys = 1
    else:
        ys = -1
    for x in range(int(round(x0)), int(math.ceil(x1))):
        if steep:
            plot(y,x)
        else:
            plot(x,y)
        err = err - dy
        if err < 0:
            y = y + ys
            err = err + dx

# find vertices
radius = w/2
calc_vert = lambda i,F: radius * ( 1 + F(math.pi * 2 / p * i))
point = [ (calc_vert(i,math.sin),calc_vert(i,math.cos)) for i in range(p)]

# connect vertices
for i in range(p):
    x0,y0 = point[i]
    x1,y1 = point[(i + t) % p]
    line(x0,y0,x1,y1)

print "\n".join(["".join(i)for i in grid]) # print grid