Java实现 洛谷 P1980 计数问题

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int s = sc.nextInt(), x = sc.nextInt(), ans = 0, m = 1;
        while(m <= s) {
            int a = s / (m * 10), b = s / m % 10, c = s % m;

            if(x != 0) {
                if(b < x) ans += a * m;
                if(b == x) ans += a * m + c + 1;
                if(b > x) ans += (a + 1) * m;
            } else {
                if(b != 0) ans += a * m;
                else ans += (a - 1) * m + c + 1;
            }
            m *= 10;
        }
        System.out.println(ans);
        sc.close();
    }
}