1 class Solution: 2     # @param num, a list of integer 3     # @return a list of lists of integers 4     def doSth(self, num): 5         result = self.permute(num[1:]) 6         for lst in result: 7             for i in range(len(lst) + 1): 8                 yield lst[:i] + num[:1] + lst[i:] 9 10     def permute(self, num):11         if len(num) == 0: return []12         if len(num) == 1: return [num]13 14         return list(self.doSth(num))