poj 2115 C Looooops

扩展的欧几里得算法……

链接http://poj.org/problem?id=2115

 1 #include<iostream>

 2 #include<stdio.h>

 3 #include<algorithm>

 4 #include<vector>

 5 #include<cmath>

 6 #include<iomanip>

 7 #include<string>

 8 using namespace std;

 9 __int64 extend_gcd(__int64 a,__int64 b,__int64 &x,__int64 &y)

10 {

11     __int64 d;

12     if(b==0)

13     {

14         x=1;

15         y=0;

16         return a;

17     }

18     else

19     {

20         d=extend_gcd(b,a%b,x,y);

21         __int64 temp=x;

22         x=y;

23         y=temp-a/b*y;

24     }

25     return d;

26 }

27 int main()

28 {

29     __int64 x,y,ans,m,n,l,i,a,b,k,c;

30     scanf("%I64d%I64d%I64d%I64d%I64d",&x,&y,&m,&n,&l);

31         k=n-m;c=x-y;

32         if(k<0)

33         {

34             k=-k;

35             c=-c;

36         }

37         i=extend_gcd(k,l,a,b);

38         if((x-y)%i)

39             cout<<"Impossible\n"<<endl;

40         else 

41         {

42             ans=(c)/i*a%l+l;

43             ans=(ans)%(l/i);

44             printf("%I64d\n",ans);

45         }

46     return 0;

47 }

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