#P16783. [蓝桥杯 2026 国 A] 密钥提取

    ID: 19124 远端评测题 1000ms 512MiB 尝试: 0 已通过: 0 显示难度普及 上传者: 标签>数学高精度提交答案2026蓝桥杯国赛

[蓝桥杯 2026 国 A] 密钥提取

Problem Description

Xiao Lan is doing a security evaluation for an encryption algorithm based on big integer multiplication. During the evaluation, he uses this algorithm to generate two special keys AA and BB:

  • Key AA consists of 2026060620260606 digits 99, that is, A=99...920260606 digitsA = \underbrace{99...9}_{20260606\text{ digits}}.
  • Key BB consists of 20262026 digits 99, that is, B=99...92026 digitsB = \underbrace{99...9}_{2026\text{ digits}}.

By computing their product, Xiao Lan gets an extremely long combined key S=A×BS = A \times B.

To verify the integrity of this key during transmission, Xiao Lan needs to extract the digits at specific positions in the decimal representation of SS (counting from left to right, with no leading zeros). Let d1,d2,d3d_1, d_2, d_3 be the digits at the 20262026-th, 2026052320260523-rd, and 2026263220262632-nd positions of SS, respectively.

Now, please find the value of the three-digit integer d1d2d3\overline{d_1 d_2 d_3} formed by these three extracted digits in order. Here d1d_1 is the hundreds digit (it is guaranteed that d10d_1 \ne 0), d2d_2 is the tens digit, and d3d_3 is the ones digit. For example, if the three extracted digits are d1=2,d2=5,d3=7d_1 = 2, d_2 = 5, d_3 = 7, then the answer you should submit is 257257.

Output Format

This is an output-only (fill-in-the-blank) problem. You only need to compute the result and submit it. The result of this problem is an integer. When submitting, you only need to write a program that outputs this integer. Any extra content will result in no score.



Hint

Translated by ChatGPT 5