题目链接
参考
方法1 回溯
方法2 递归
image.png
class Solution(object):
def combine(self, n, k):
if k>n or k==0:
return []
if k==1:
return [[i] for i in range(1,n+1)]
if k==n:
return [[i for i in range(1,n+1)]]
answer=self.combine(n-1,k)
for item in self.combine(n-1,k-1):
item.append(n)
answer.append(item)
return answer
