78. Subsets
class Solution:
def subsets(self, nums: List[int]) -> List[List[int]]:
res = []
n = len(nums)
def backtrack(curr, start):
res.append(list(curr))
for i in range(start, n):
curr.append(nums[i])
backtrack(curr, i + 1)
curr.pop()
backtrack([], 0)
return res