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)