LeetCode 筆記 - 278-First-Bad-Version

# The isBadVersion API is already defined for you.
# def isBadVersion(version: int) -> bool:

class Solution:
    def firstBadVersion(self, n: int) -> int:
        
        if n == 1:
            return 1
        
        start = 0
        end = n
        
        while start <= end:
            mid = int((start + end) / 2)
            
            if isBadVersion(mid):
                end = mid - 1
            elif isBadVersion(mid + 1):
                return mid + 1
            else:
                start = mid + 1
        
        return -1