47. Permutations II.py

class Solution:
    def permuteUnique(self, nums: List[int]) -> List[List[int]]:
        ans = []
        # base
        if len(nums)==1:
            return [nums[:]] 
        
        for i in range(len(nums)): # counter
            tmp=nums.pop(0)
            res=self.permuteUnique(nums)
            for j in res:
                j.append(tmp)
            
            another_ = []
            for re in res:
                if re not in ans:
                    another_.append(re)
            ans.extend(another_)     
            nums.append(tmp) 
        return ans