# Leetcodde problem - https://leetcode.com/problems/permutations/
perms = []
def permHelper(nums, chosen):
        # print('permHelper(', nums , ', ' , chosen , ')', sep = "")
        # if-else
        if len(nums) == 0:
            print(chosen)               # this line prints the permutation correctly
            perms.append(chosen)        # but perms returning list of empty lists!
        else:
            for i in range(len(nums)):
                # choose
                n = nums[i]
                nums.remove(n)
                chosen.append(n)

                # explore
                permHelper(nums, chosen)

                # un-choose
                nums.insert(i, n)
                chosen.remove(n)
        # return perms

class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        permHelper(nums, [])
        return perms