278 First Bad Version
278. First Bad Version
题目： https://leetcode.com/problems/first-bad-version/
难度 : Easy
思路：
根据 search for a range 改的
class Solution(object):
def firstBadVersion(self, n):
"""
:type n: int
:rtype: int
"""
l, r = 0, n - 1
while l <= r:
mid = l + ((r - l) >> 2)
if not isBadVersion(mid):
l = mid + 1
else:
r = mid - 1
return l
