这个代码是画蛇添足，根本不需要自己模拟进位。

class PartialSolution:
def __init__(self, n):
self.list = [''] * n
def enumInts(self, current, begin):
if current == len(self.list):
print(''.join(self.list))
else:
for i in range(begin, 10):
self.list[current] = str(i)
self.enumInts(current + 1, 0)

class Solution:
def solve(self, n):
if n >= 1:
PartialSolution(1).enumInts(0, 0)
if n >= 2:
for i in range(2, n + 1):
PartialSolution(i).enumInts(0, 1)

Solution().solve(0)
print('----')
Solution().solve(1)
print('----')
Solution().solve(2)

如果缩进被吃了你可以自己通过逻辑来还原正确的缩进