[LeetCode] 278. 第一个错误的版本

二分寻找边界

public class Solution extends VersionControl {
    public int firstBadVersion(int n) {
        int i = 1;
        int j = n;
        while (i<=j) {
            int mid = i + ((j-i)>>1);
            boolean ret = isBadVersion(mid);
            if (ret == true) {
                j = mid - 1;
            } else {
                i = mid + 1;
            }
        }

        return i;
    }
}