hdu 1576 A/B

原题链接：hdu 1576 A/B

同样是用扩展的欧几里得算法。A = 9973k+n = xB，从而转化为：xB-9973k=n求解x即可。

具体扩展欧几里得算法请参考：hdu 2669 Romantic

代码如下：

 1 #include <cstdio>

 2 #include <cstdlib>

 3 #include <iostream>

 4 #include <cstring>

 5 #define     MOD 9973

 6 using namespace std;

 7 typedef long long LL;

 8 void exgcd(LL a, LL b, LL &d, LL &x, LL&y)

 9 {

10     if( b == 0 )

11     {

12         d = a;

13         x = 1;

14         y = 0;

15     }

16     else

17     {

18         exgcd(b, a%b, d, x, y);

19         int t = x;

20         x = y;

21         y = t - (a/b)*y;

22     }

23 }

24 int main(int argc, char *argv[])

25 {

26     int T;

27     scanf ( "%d", &T );

28     int n, a, b;

29     LL d, x, y;

30     while( T-- )

31     {

32         scanf("%d%d", &n, &b);   

33         a = MOD;

34         exgcd(a, b, d, x, y);

35         y = (y%MOD)*(n/d)%MOD;

36         y = (y+MOD)%MOD;

37         cout<<y<<endl;

38     }

39 }