subsets2.py

class Solution(object):
    def subsetsWithDup(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        nums = sorted(nums)
        result = []
        temp = []
        self.backtrack(nums, result, temp, 0)
        return result
    def backtrack(self, nums, result, temp, start):
        result.append(temp[:])
        for i in range(start, len(nums)):
            if i > start and nums[i] == nums[i - 1]: continue
            temp.append(nums[i])
            self.backtrack(nums, result, temp, i + 1)
            temp.pop()