first-bad-version.java

/* The isBadVersion API is defined in the parent class VersionControl.
      boolean isBadVersion(int version); */

public class Solution extends VersionControl {
    public int firstBadVersion(int n) {
        
        int low=0;
        int high=n-1;
        while(low<=high)
        {
            int mid=low+(high-low)/2;
            if((isBadVersion(mid)==true))
                high=mid-1;
            else
                low=mid+1;
        }
        return low;
    }
}