0 1 4
0 2 3
1 4 7
5 3 8

class Node():
    def __init__(self, v, w, next=None):
        self.v = v
        self.w = w
        self.next = next
    ...

class LinkedList():
    def __init__(self, head=None)
        self.head = head

    def add_node():
        pass
    ...

0 -> [1:4]-> [2:3]
1 -> [4:7]
2 -> []
3 -> []
4 -> []
5 -> [3:8]

g = [LinkedList_for_0, LinkedList_for_1, ...]

g = [[] for v in range(number_of_vertex)]
for f, t, w in edges:
    g[f].add_node(Node(t,w))

class Node():
    def __init__(self, v, w):
        self.v = v
        self.w = w

[Node(1,4), Node(2,3)]

[
 [Node(1,4), Node(2,3)],
 [Node(0,4), Node(4,7)],
 [Node(0,3)],
 [Node(5,8)],
 [Node(1,7)],
 [Node(3,8)]
]

g = [[] for v in range(number_of_vertex)]
for f,t,w in edges:
    g[f].append(Node(t,w))
    g[t].append(Node(f,w))

adjacency_list = {}
for line in open(file):
    from, to, weight = map(int, line.split())
    adjacency_list.setdefault(from, {})[to] = weight
    adjacency_list.setdefault(to, {})[from] = weight  # for undircted graph add reverse edges

import networkx as nx

G=nx.Graph()

for line in file:
    a, b, w = map(int, line.strip().split(' '))
    G.add_edge(a, b, weight=w)

from collections import defaultdict

adj = defaultdict(list)

content = open('input.txt', 'r').readlines()

for line in content:
    u, v, w = map(int, line.strip().split(' '))
    # if edge is on-way
    adj[u].append((v, w))
    # otherwise,
    adj[u].append((v, w))
    adj[v].append((u, w))