QOJ.ac

QOJ

حد الوقت: 8.0 s حد الذاكرة: 512 MB مجموع النقاط: 100 قابلة للهجوم ✓

#9139. 前缀能被后缀整除

الإحصائيات

给定两个正整数 $n$ 和 $c$。

考虑一个正整数 $x$,其十进制表示为 $x = \overline{(x_{k-1}x_{k-2} \dots x_1x_0)_{10}}$(无前导零)。如果 $x$ 的十进制表示可以被划分为非空前缀 $p = \overline{(x_{k-1} \dots x_i)_{10}}$ 和非空后缀 $s = \overline{(x_{i-1} \dots x_0)_{10}}$(对于某个 $0 < i \le k-1$),使得 $p$ 能被 $s + c$ 整除,则称该数 $x$ 为“好数”。注意,$x_{i-1} = 0$ 是允许的。

计算从 $1$ 到 $n$ 的好数的个数。

输入格式

仅一行,包含两个正整数 $n$ 和 $c$ ($1 \le n \le 10^{14}$, $1 \le c \le 10^4$)。

输出格式

输出一个整数,表示从 $1$ 到 $n$ 的好数的个数。

样例

样例输入 1

20 1

样例输出 1

2

样例输入 2

111 4

样例输出 2

9

样例输入 3

1111 10

样例输出 3

75

样例输入 4

1000000 7

样例输出 4

111529

说明

在第一个测试中,好数为 $10, 20$。

在第二个测试中,好数为 $40, 51, 62, 73, 80, 84, 95, 101, 106$。

Discussions

About Discussions

The discussion section is only for posting: General Discussions (problem-solving strategies, alternative approaches), and Off-topic conversations.

This is NOT for reporting issues! If you want to report bugs or errors, please use the Issues section below.

Open Discussions 0
No discussions in this category.

Issues

About Issues

If you find any issues with the problem (statement, scoring, time/memory limits, test cases, etc.), you may submit an issue here. A problem moderator will review your issue.

Guidelines:

  1. This is not a place to publish discussions, editorials, or requests to debug your code. Issues are only visible to you and problem moderators.
  2. Do not submit duplicated issues.
  3. Issues must be filed in English or Chinese only.
Active Issues 0
No issues in this category.
Closed/Resolved Issues 0
No issues in this category.