First Bad Version

You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the previous version, all the versions after a bad version are also bad. Suppose you have `n` versions `[1, 2, ..., n]` and you want to find out the first bad one, which causes all the following ones to be bad. You are given an API `bool isBadVersion(version)` which returns whether `version` is bad. Implement a function to find the first bad version. You should minimize the number of calls to the API.   **Example 1:** **Input:** n = 5, bad = 4 **Output:** 4 **Explanation:** call isBadVersion(3) -> false call isBadVersion(5) -> true call isBadVersion(4) -> true Then 4 is the first bad version. ``` **Example 2:** **Input:** n = 1, bad = 1 **Output:** 1 ```   **Constraints:** - `1 <= bad <= n <= 231 - 1`