leetcode278.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 start = 1;
        int end = n;
        while(start < end)
        {
        	int mid = start + (end - start) / 2;
        	if(isBadVersion(mid) == true)
        		end = mid;
        	else
        		start = mid + 1;
        }
        return start;
    }
}