题目:
题解:
python
class Solution:
def lastRemaining(self, n: int) -> int:
a1 = 1
k, cnt, step = 0, n, 1
while cnt > 1:
if k % 2 == 0: # 正向
a1 += step
else: # 反向
if cnt % 2:
a1 += step
k += 1
cnt >>= 1
step <<= 1
return a1