Permutations Recusive

permutations_recursive.py

class Solution:

    def permute(self, nums: List[int]) -> List[List[int]]:
        result = []
        
        def permute_helper(ans: List[int], cur: List[int], options: List[int]):
            if len(options) == 0:
                ans.append(cur)
            else:
                for index, choice in enumerate(options):
                    permute_helper(ans, cur + [choice], options[:index] + options[index + 1:])
                
        permute_helper(result, [], nums)
        
        return result