# Tk_avoidance_walk_5.py

# Tk_avoidance_walk_5.py

import random
from Tkinter import *
from math import *

ri = random.randint
rs = random.shuffle
rc = random.choice

ww = 600
hh = 600

root = Tk()
root.title("Tk_avoidance_walk")
root.geometry("%dx%d+-6+-2"%(ww,hh))
cv = Canvas(width=ww, height=hh, bg='white')
cv.pack()

steps = ["N","E","S","W"]

r = 10
grid = dict([((x,y), 0) for x in range(r,ww-r) for y in range(r,hh-r)])
xy__ = x,y = ww/2, hh/2
xy = [(x,y)]
total = 1
grid[x,y] = total
path = [steps[:]]

while 1:
    x,y = xy[-1]
    ttt = []
    vvv = ((x,y-r),(x+r,y),(x,y+r),(x-r,y))
    for x2,y2 in vvv:
        if (x2,y2) in grid:
            step = steps[vvv.index((x2,y2))]
            try:
                if not grid[x2,y2] and (step in path[-1]):
                    ttt += [(x2, y2, step)]
            except:
                0
    if ttt:
        x2,y2,ttt = rc(ttt)
        total = total+1
        grid[x2,y2] = total
        path[-1].remove(ttt)
        xy.append((x2,y2))
        path.append((steps[:]))
    else:
        path.pop()
        xy.pop()

    if step:
        try:
            cv.create_line(xy[-2:],fill='red')
        except:
            break
        cv.update()

xy = [xy__]
Lx, Ly = max(grid.keys())
L = (Lx/5)*(Ly/5)

paths = []
block = {}
LXY = 20
while 1:
    p = []
    xy2 = [xy[-1]]
    for i in range(LXY+1):
        x,y = xy2[-1]
        ttt = []
        vvv = [(x,y-r),(x+r,y),(x,y+r),(x-r,y)]
        for x2,y2 in vvv:
            if (x2,y2) in grid:
                if (x2,y2) not in xy+xy2:
                    ttt += [(grid[x2,y2],x2,y2)]
                    grid[x2,y2] = 0
        if ttt:
            zzz,x2,y2 = min(ttt)

            xy2 += [(x2,y2)]
            grid[x2,y2] += len(xy)

            cv.delete('all')
            cv.create_line(xy+xy2,fill='blue')
            cv.update()
        else:
            xy2 = []
            break

    if xy2:
        xy.extend(xy2[:-1])
    else:
        t = LXY
        try:
            block[x,y] += t*2
            block = block[-2000:]
        except:
            block[x,y] = t
        t = block[x,y]

        if xy[:-t*2]:
            xy = xy[:-t*2]
        else:
            xy = [xy[0]]

    # print len(xy)