poj 1061 青蛙的约会

扩展欧几里德算法的练习题，直接调用exgcd函数就可以了

 1 #include<iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<cstdlib>

 5 #include<algorithm>

 6 #define inf 0x7fffffff

 7 using namespace std;

 8 

 9 typedef long long LL;

10 LL x,y,m,n,L;

11 LL x1,y1;

12 LL q;

13 void exgcd(LL a,LL b)

14 {

15     //cout<<a<<endl;

16     if (!b) {x1=1 ;y1=0 ;q=a ; }

17     else

18     {

19         exgcd(b,a%b);

20         LL temp=x1 ;x1=y1 ;y1=temp-a/b*y1;

21     }

22 }

23 LL gcd(LL a,LL b) {return b==0 ? a : gcd(b,a%b); }

24 int main()

25 {

26     while (cin>>x>>y>>m>>n>>L) {

27     LL d=y-x;

28     LL gcd=1;

29     exgcd(n-m,L);

30     gcd=q;

31     if (d%gcd) cout<<"Impossible"<<endl;

32     else

33     {

34         x1 *= (x-y)/gcd;

35         x1=(x1%(L/gcd)+(L/gcd))%(L/gcd);

36         cout<<x1<<endl;

37     }

38     }

39     return 0;

40 }