mirror of
https://github.com/devenperez/leetcode.git
synced 2026-06-13 23:07:08 +00:00
Deven
29 lines
1013 B
Python
29 lines
1013 B
Python
class Solution:
|
|
def subsets(self, nums: List[int]) -> List[List[int]]:
|
|
|
|
# All subsets can be mapped to a binary number where
|
|
# - the number is the same length as the list
|
|
# - a 1 represents the number being in the list, 0 otherwise
|
|
|
|
# Example: nums = [1,2,3]
|
|
# subsetBinary = 0 = 0b000 -> []
|
|
# = 3 = 0b011 -> [2, 3]
|
|
# (2 ** 3) - 1 = 7 = 0b111 -> [1, 2, 3]
|
|
|
|
import math
|
|
powerSet = []
|
|
|
|
for subsetBinary in range(2 ** len(nums)):
|
|
subset = []
|
|
|
|
# Iterates exactly n times (where n is the number of 1s in the binary string)
|
|
while subsetBinary > 0:
|
|
indexOfFirst1 = -(math.floor(math.log2(subsetBinary)) + 1)
|
|
|
|
subset.append(nums[indexOfFirst1])
|
|
|
|
subsetBinary -= 2 ** (-indexOfFirst1 - 1)
|
|
|
|
powerSet.append(subset)
|
|
|
|
return powerSet |