#Leet Code# Permutation

 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))