lower

    /**
     * 小于索引的最大值
     *
     * @param data
     * @param target
     * @param <E>
     * @return
     */
    public static <E extends Comparable<E>> int lower(E[] data, E target) {
        int l = -1, r = data.length - 1;
        while (l < r) {
            // mid向上取整 避免相邻情况下的问题
            int mid = l + (r - l + 1) / 2;
            if (data[mid].compareTo(target) <= 0) {
                l = mid;
            } else {
                r = mid - 1;
            }
        }
        return l;
    }