Coding interview problem : find the longest consecutive sequence in a sequence.

longest_consecutive_sequence.py

# You have to return the longest consecutive sequence of numbers in an array.
# If the input is [2, 1, 6, 9, 4, 3], the output must be [1, 2, 3, 4]
# O(n)

def longestSequence(sequence):
	hashtable = {}
	longest = []
	for i in range(0, len(sequence)):
		hashtable[sequence[i]] = True
	for number in hashtable:
		if number - 1 not in hashtable: 		# If the current number is a minimum
			current = number
			longest_tmp = []
			while (current in hashtable): 		# While there's a number following the current one
				longest_tmp.append(current)
				current += 1
			if len(longest_tmp) > len(longest):
				longest = longest_tmp
	return longest



print longestSequence([2, 1, 6, 9, 4, 3])