These files are the python implementation of the union find algoritm and it's unit tests.

test_union_find.py

#!/usr/bin/env python

import unittest
from union_find import UnionFind

class TestUnionFind(unittest.TestCase):

	def test_init(self):
		u = UnionFind(5)
		self.assertEquals([0, 1, 2, 3, 4], u.id)

	def test_connected(self):
		u = UnionFind(5)
		u.id[1] = u.id[2]
		self.assertTrue(u.connected(1, 2))
		self.assertTrue(u.connected(2, 1))
		self.assertTrue(u.connected(2, 2))
		self.assertTrue(u.connected(1, 1))

	def test_not_connected(self):
		u = UnionFind(5)
		self.assertFalse(u.connected(1, 2))

	def test_union(self):
		u = UnionFind(5)
		u.union(1, 2)
		self.assertEquals(u.id[1], u.id[1])
		self.assertEquals(u.id[1], u.id[2])
		self.assertEquals(u.id[2], u.id[1])


if __name__ == '__main__':
	unittest.main()

union_find.py

#!/usr/bin/env python

class UnionFind():

	def __init__(self, size):
		self.id = [i for i in xrange(size)]

	def connected(self, a, b):
		return self.id[a] == self.id[b]

	def union(self, a, b):
		first = self.id[a]
		second = self.id[b]
		for i in self.id: 
			if self.id[i] == first:
				self.id[i] = second