46   69      ------- 46 вершин, 69 ребер;
 0   1 
 0   2 
 0   3 
 1   26 
 1   4 
 2   10 
 2   11 
 3   18 
 3   19 
 4   5 
 4   33 
 5   29 
 5   6 
 6   27 
 6   7 
 7   8 
 7   14 
 8   9 
 8   38 
 9   10 
 9   37 
 10   39 
 11   12 
 11   39 
 12   35 
 12   13 
 13   14 
 13   15 
 14   34 
 15   16 
 15   22 
 16   17 
 16   44 
 17   18 
 17   43 
 18   45 
 19   20 
 19   45 
 20   41 
 20   21 
 21   22 
 21   23 
 22   40 
 23   24 
 23   27 
 24   32 
 24   25 
 25   26 
 25   31 
 26   33 
 27   28 
 28   32 
 28   29 
 29   30 
 30   33 
 30   31 
 31   32 
 34   35 
 34   38 
 35   36 
 36   37 
 36   39 
 37   38 
 40   41 
 40   44 
 41   42 
 42   43 
 42   45 
 43   44 

# Список пар имен "родитель - рибеног":
t = (\
    ('H','E'),('A','S'),('A','B'),('C','I'),('C','J'),('C','U'),
    ('Z','C'),('Z','F'),('Z','M'),('M','R'),('M','A'),('M','T'),
    ('F','H'),('F','W'),('W','N'),('H','O'),('H','P'),('M','K'),
    ('R','G'),('R','Y'),('R','V'),('V','D'),('V','X')
    )


from Tkinter import *

def show_tree(a):
    map1, map2, names = {}, {}, set([])
    for ai in a:
        names.add(ai[ 0 ])
        names.add(ai[ 1 ])
        if map1.has_key(ai[ 0 ]):
            map1[ai[ 0 ]].add(ai[ 1 ])
        else:
            map1[ai[ 0 ]] = set([ai[ 1 ]])
        if map2.has_key(ai[ 1 ]):
            map2[ai[ 1 ]].add(ai[ 0 ])
        else:
            map2[ai[ 1 ]] = set([ai[ 0 ]])            
    for name in names:
        if not map2.has_key(name):
            root = name
            break

    WIDTH =  1000 
    HEIGHT =  800 
    NODE_DX =  14 
    NODE_DY =  10 
    NODE_COLOR = 'white'
    EDGE_COLOR = 'blue'
    TEXT_COLOR = 'red'
    
    rt = Tk()
    rt.resizable(True, True)
    rt.title('my_graphviz_tree')
    left = (rt.winfo_screenwidth() - WIDTH) /  2 
    top = (rt.winfo_screenheight() - HEIGHT) /  2 
    rt.geometry('%dx%d+%d+%d' % (WIDTH, HEIGHT, left, top))
    pic = Canvas(rt, width=WIDTH, height=HEIGHT, background='white')
    pic.pack()
    pic.delete(ALL)

    map3 = {}
    root_x, root_y = WIDTH /  2 ,  40 
    map3[root] = [root_x, root_y]

    def foo(parent, x, y, lev):
        if not map1.has_key(parent):
            return
        children = map1[parent]
        y1 = y +  120  *  0 . 8 **lev
        dx =  240  *  0 . 33 **lev
        if len(children) !=  1 :
            x1 = x - dx * (len(children) -  1 ) /  2 
        else:
            x1 = x
        for child in children:
            map3[child] = [x1, y1]
            foo(child, x1, y1, lev +  1 )
            x1 += dx

    def draw_edges(parent):
        if not map1.has_key(parent):
            return
        children = map1[parent]
        x1, y1 = map3[parent]
        for child in children:
            x2, y2 = map3[child]
            pic.create_line((x1, y1, x2, y2), fill=EDGE_COLOR, width= 2 )
            draw_edges(child)

    def draw_nodes():
        for key in map3.keys():
            x, y = map3[key]
            pic.create_oval((x - NODE_DX, y - NODE_DY, x + NODE_DX, y + NODE_DY), fill=NODE_COLOR)
            pic.create_text((x, y), text=str(key), fill=TEXT_COLOR)
    
    foo(root, root_x, root_y,  0 )
    draw_edges(root)
    draw_nodes()

    y =  20 
    for ai in a:
        y +=  16 
        pic.create_text(( 60 , y), text=str(ai[ 0 ])+'   ->   '+str(ai[ 1 ]), fill='black')

    pic.update()
    rt.mainloop()


show_tree(t)