[binary search - simple] 278 First wrong version

【 subject 】
Example 1：

Input ：n = 5, bad = 4
Output ：4
explain ：
call isBadVersion(3) -> false
call isBadVersion(5) -> true
call isBadVersion(4) -> true
therefore ,4 It's the first wrong version .

Example 2：

Input ：n = 1, bad = 1
Output ：1

Tips ：

1 <= bad <= n <= 231 - 1

【 Code 】
Execution time ：36 ms, In all Python3 Defeated in submission 61.83% Users of
Memory consumption ：14.9 MB, In all Python3 Defeated in submission 27.64% Users of
Pass the test case ：22 / 22

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

class Solution:
    def firstBadVersion(self, n):
        """ :type n: int :rtype: int """
        left,right=1,n
        while left<right:
            mid=left+(right-left)//2
            if isBadVersion(mid)==True:
                right=mid
            else:
                left=mid+1
        return left