class Solution(object):

def subsets(self, nums):

"""

:type nums: List[int]

:rtype: List[List[int]]

"""

# Using itertools combinations - Short and easy logic - 100 pass

import itertools

result = []

for i in range(len(nums)+1):

for comb in itertools.combinations(nums,i): # use permutation when order is important as in (2,1) != (1,2)

result.append(comb)

return result

"""

# Learn about BackTracking technique

# Recursion method without itertools --> Just to make sure its implementable in other languages - 100 pass

def combinations(ans, nums):

for i,v in enumerate(nums):

value = ans + [v]

result.append(value)

combinations(value, nums[i+1:])

result = [[]] # Adding the empty set as the first entry without any elements

combinations([], nums)

return result

"""