Use combinations & Union Find Algo

union_find.py

from itertools import combinations

N,l = map(int,raw_input().split())

sets = []

idx = dict((i, i) for i in range(N))

for i in xrange(l):
	a,b = map(int,raw_input().split())
	val = idx[a]
	for i in idx:
		if idx[i] == val:
			idx[i] = idx[b]
sets = {}
for val in set(idx.values()):
	sets[val] = set([])
	for i in idx.keys():
		if idx[i] == val:
			sets[val].add(i)

total = 0
for g in combinations(sets.values(), 2):
	total += len(g[0]) * len(g[1])

print total

N,l = map(int,raw_input().split())

sets = []

idx = dict((i, i) for i in range(N))
print idx

for i in xrange(l):
a,b = map(int,raw_input().split())
set_a = set([a])
set_b = set([b])

for s in sets:
    if a in s:
        mark = True
        s.add(b)
    if b in s:
        mark = True
        s.add(a)
if not mark:
    s = set([a, b])
    sets.append(s)