GraphBuilder

from PIL import Image, ImageFilter, ImageDraw, ImageFont
from math import *

def gen_graph(g, w, h):
    n = len(g)
    white = (255, 255, 255)
    black = (0, 0, 0)
    green = (0, 255, 0)
    img = Image.new('RGB', (w, h), white)
    arr = img.load()

    circle_size = 40
    circle = (0, 0, 40, 40)

    pts = []

    pi = acos(-1)

    for i in range(n):
        x = cos(2 * pi * i / n)
        y = sin(2 * pi * i / n)
        lenx = (w - circle_size) / 2
        x *= lenx
        leny = (h - circle_size) / 2
        y *= leny
        x += w / 2
        y += h / 2
        pts.append((int(x),int(y)))



    draw = ImageDraw.Draw(img)
    print('ok')

    for v in range(n):
        for u in g[v]:
            if type(u) == type(1):
                draw.line([pts[v], pts[u]], fill=black, width=3)
                x, y = pts[u]
                dx = pts[v][0] - pts[u][0]
                dy = pts[v][1] - pts[u][1]
                l = (dx * dx + dy * dy) ** 0.5
                if l == 0:
                    continue
                dx /= l
                dy /= l
                K = circle_size / 2
                x += dx * K
                y += dy * K
                sz = 5
                draw.rectangle([x-sz, y-sz, x+sz, y+sz], fill=green, outline=black)
            elif type(u) == type((1,1)):
                w = u[1]
                u = u[0]
                draw.line([pts[v], pts[u]], fill=black, width=3)
                coord = ((pts[v][0] + pts[u][0]) // 2 + 15, (pts[v][1] + pts[u][1]) // 2)
                draw.text(coord, str(w), font=ImageFont.load_default(), fill=black)
                x, y = pts[u]
                dx = pts[v][0] - pts[u][0]
                dy = pts[v][1] - pts[u][1]
                l = (dx * dx + dy * dy) ** 0.5
                if l == 0:
                    continue
                dx /= l
                dy /= l
                K = circle_size / 2
                x += dx * K
                y += dy * K
                sz = 5
                draw.rectangle([x-sz, y-sz, x+sz, y+sz], fill=green, outline=black)
            else:
                continue
    index = 0
    for (x, y) in pts:
        index += 1
        x1, y1, x2, y2 = circle
        draw.ellipse([x + x1 - circle_size // 2,
                      y + y1 - circle_size // 2,
                      x + x2 - circle_size // 2,
                      y + y2 - circle_size // 2
                     ], fill=white, outline=black)
        draw.text((x, y), str(index), font=ImageFont.load_default(), fill=black)
    img.show()


def parse_graph(n, s):
    g = [[] for _ in range(n)]
    s = s.split('\n')
    for edge in s:
        if len(edge) == 0:
            continue
        edge = list(map(int, edge.split()))
        f = edge[0] - 1
        t = edge[1] - 1
        if len(edge) == 3:
            w = edge[2]
            g[f].append((t, w))
        else:
            g[f].append(t)
    return g

s = """1 2 10
2 3 5
1 3 100
3 5 7
5 4 10
4 3 -18
6 1 -1"""
graph = parse_graph(6, s)
gen_graph(graph, 500, 500)