# nums = list

def permuteUnique(self, nums):
    res, visited = [], [False]*len(nums)
    nums.sort()
    self.dfs(nums, visited, [], res)
    return res
    
def dfs(self, nums, visited, path, res):
    if len(nums) == len(path):
        res.append(path)
        return 
    for i in xrange(len(nums)):
        if not visited[i]: 
            if i>0 and not visited[i-1] and nums[i] == nums[i-1]:  # here should pay attention
                continue
            visited[i] = True
            self.dfs(nums, visited, path+[nums[i]], res)
            visited[i] = False