拉一坨大的
好爽==
一二三四五
数学解到底沙小
def findKthBit(self, n: int, k: int) -> str:
def invert(s):
tmp = ""
for c in s:
if c=="1":
tmp += "0"
else:
tmp += "1"
return tmp
def helper(prev, k):
if k==0:
return "1"
elif k<=len(prev):
if prev[-k]=="1":
return "0"
else:
return "1"
else:
return helper(prev+"1"+invert(prev)[::-1], k-len(prev)-1)
if k==1:
return "0"
else:
return helper("0", k-2)