Subsets

Given a set ofdistinctintegers,nums, return all possible subsets.

Note:The solution set must not contain duplicate subsets.

For example,
Ifnums=[1,2,3], a solution is:

[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

Solution

DFS visit each subset from start index to len(nums). Logic graph below

Why mistaken for so long?

1. typo. Bad habit. Never copy paste code. If you want to, it probably means you need a helper function
2. Bad habit. Need to keep the coding variable name consistent. Because don't change variable meaning in different functions

class Solution(object):
    def subsets(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """

        n = len(nums)
        res = [[]]

        for start in range(n):
            self.dfsVisit(start + 1, nums, res, [nums[start]])

        return res

    def dfsVisit(self, start, nums, res, cur):


        if start > len(nums):
            return
        res.append(cur[:])
        for i in range(start, len(nums)):

            self.dfsVisit(i + 1, nums, res, cur + [nums[i]])