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:
    def firstBadVersion(self, n):
        """
        :type n: int
        :rtype: int
        """
        left = 1
        right = n
        mid = (left + right) // 2
        while 1:
            if  isBadVersion(mid) and not isBadVersion(mid-1):
                return mid
            elif isBadVersion(mid) and isBadVersion(mid-1):
                right = mid - 1
                mid = (left + right) // 2
            elif not isBadVersion(mid) and isBadVersion(mid+1):
                return mid+1
            else:
                left = mid + 1
                mid = (left + right) // 2

'''
    This is my personal record of solving Leetcode Problems. 
    If you have any questions, please discuss them in [Issues](https://github.com/mengxinayan/leetcode/issues).
    Copyright (C) 2020-2022  mengxinayan

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
'''