1     /**
 2      * 求逆元
 3      * ax = 1 (% mo),gcd(a,mo)=1
 4      * ax+mo*y=1
 5      * */
 6     public static long inverseElement(long a, long mo) throws Exception {
 7
 8       long d = linearEquation(a, mo, 1);//ax+mo*y=1
 9       x = (x % mo + mo) % mo;//保证x>0
10       return d;
11     }

 1 import java.util.Scanner;
 2
 3 /**
 4  * (A/B)%9973,求余,除法不满足交换性,可改为求B关于9973的逆元x,
 5  * 这样结果等价于Ax%9973等价于x*A%9973等价于xn%9973,
 6  */
 7
 8 public class HDU1576 {
 9
10     public static void main(String[] args) {
11         Scanner scanner = new Scanner(System.in);
12         int T = scanner.nextInt();
13         for (int i = 0; i < T; i++) {
14             int n = scanner.nextInt();
15             int b = scanner.nextInt();
16             try {
17                 MyGcd.inverseElement(b, 9973);
18                 long x = MyGcd.x;
19                 System.out.println(x*n%9973);
20             } catch (Exception e) {
21                 // TODO: handle exception
22             }
23         }
24     }
25
26     private static class MyGcd{
27         static long x;
28         static long y;
29
30         public static long gcd(long m, long n) {
31             return n == 0 ? m : gcd(n, m % n);
32         }
33
34         public static long ext_gcd(long a,long b){
35             if (b==0) {
36                 x = 1;
37                 y = 0;
38                 return a;
39             }
40             long res = ext_gcd(b, a % b);
41             long x1 = x;
42             x = y;
43             y = x1 - a / b * y;
44             return res;
45         }
46
47         public static long linearEquation(long a, long b, long m) throws Exception {
48             long d = ext_gcd(a, b);
49             if (m % d != 0) {
50                 throw new Exception("无解");
51             }
52             long n = m / d;
53             x *= n;
54             y *= n;
55             return d;
56         }
57
58         public static long inverseElement(long a, long mo) throws Exception {
59
60             long d = linearEquation(a, mo, 1);// ax+mo*y=1
61             x = (x % mo + mo) % mo;// 保证x>0
62             return d;
63         }
64     }
65 }