python第一个为1的数

list=[0,0,0,0,1,1,1…]
二分查找+递归

# The isBadVersion API is already defined for you.
# @param version, an integer
# @return an integer
# def isBadVersion(version):

class Solution:
    def firstBadVersion(self, n):
        """
        :type n: int
        :rtype: int
        """
        if n== 1:
            return 1

        return self.firstBadVersionHelper(1,n)
        
    def firstBadVersionHelper(self,start,end):
        if end == start:
            return start
        mid =(start+end) >>1
        a = isBadVersion(mid)
       #区间判断
        if a:
            idx = self.firstBadVersionHelper(start=start,end=mid)#左区间，包括中点
        else:
            idx = self.firstBadVersionHelper(start=mid+1,end=end)#右区间，不包括中点

        return idx

效率还可以