278_First_Bad_Version.py

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


class Solution(object):
    def firstBadVersion(self, n):
        """
        :type n: int
        :rtype: int
        1 2 3 4

        left, right = 1, 4
        mid = 2
        """
        left, right = 1, n

        while left <= right:
            mid = left + (right - left) // 2
            if isBadVersion(mid):
                right = mid - 1
            else:
                left = mid + 1
        return left