1221 : hard math

时间限制Time Limit 1 秒Sec 内存限制Memory Limit 256 兆MB 提交次数Submitted 254 次Times 通过次数Solved 79 次Times

标准评测 Standard

从标准输入读入，结果写到标准输出。评测将输出拆成 token，与标准答案逐项比较，不按整段逐字节比对。 Read from standard input and write to standard output. The judge splits the output into tokens and compares them with the official answer; it does not compare raw bytes.

比对Compare	token 相同即通过。中间的空格、制表符、换行可多可少。Matching tokens pass. Extra spaces, tabs, or newlines between them are ignored.
不同则错Differs	token 个数或内容不同即错误。23 与 2 3、02 与 2、2.0 与 2 均视为不同。A different token count or value is wrong. 23 vs 2 3, 02 vs 2, and 2.0 vs 2 all differ.
输入Input	标准输入，格式见题面。Standard input; format as in the statement.
输出Output	标准输出。Standard output.

模板Template

C++ C Java Python

#include <iostream>
using namespace std;
int main() {
    int a, b;
    cin >> a >> b;
    cout << (a + b) << endl;
    return 0;
}

#include <stdio.h>
int main() {
    int a, b;
    scanf("%d%d", &a, &b);
    printf("%d\n", a + b);
    return 0;
}

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();
        System.out.println(a + b);
    }
}

a, b = map(int, input().split())
print(a + b)

题目描述Description

binarycopycode is terrible at math. He always ask locytus for help but after their retirement, they went to different universities for their graduate studies. So binarycopycode have to seek help from you.

We define \(f(x)\) equals to the number of distinct digits in the decimal notation of \(x\) . Now please calculate the number of \(X\) satisfied that \(L \leq X \leq R\) and \(f(X)=A\) . Print this count modulo \(10^9+7\).

输入格式Input

First line is \(n(1\leq n \leq200,000)\) which indicate that \(L\) and \(R\) both have exactly \(n\) digits.

Next 2 lines is \(L\) and \(R\) , it is guaranteed that there are no leading zeros in \(L\) and \(R\).

The last line contains 1 integers \(A\) (\(1\leq A \leq 10\)).

输出格式Output

Print the number of pairs modulo \(10^9+7\).

样例Sample

来源Source

湖南省第十九届大学生计算机程序设计竞赛（HNCPC2023）