递归和回溯_leetcode90

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

        self.res = []

        self.old = None
        self.res.append([])
        # for i in range(len(nums)):

        nums = sorted(nums)
        self.generateSub(nums, 0, [])
        print self.res

        return self.res

    def generateSub(self, nums, start, ans):

        if ans:
            self.res.append(ans[0:])


        for i in range(start, len(nums)):
            if self.old != nums[i]:
                ans.append(nums[i])
                self.generateSub(nums, i + 1, ans)
                self.old = ans.pop()
            else:
                continue




s = Solution()
nums = [1,2,2]

s.subsetsWithDup(nums)