Leetcode LCP 17. quick calculation robot Python 3

Leetcode LCP 17 The reference codes are as follows ：

class Solution:
def calculate(self, s: str) -> int:
x,y=1,0
for i in s:
if i=="A":
x=2*x+y
else:
y=2*y+x
return x+y

Topic link ：

Power button https://leetcode.cn/problems/nGK0Fy/