First Bad Version

Intuition

Solution

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

        while end - start > 1:
            mid = (start + end) // 2
            if isBadVersion(mid):
                end = mid
            else:
                start = mid
        return end