POJ1061 青蛙的约会

 1 //It is made by jump~
 2 #include <iostream>
 3 #include <cstdlib>
 4 #include <cstring>
 5 #include <cstdio>
 6 #include <cmath>
 7 #include <algorithm>
 8 #include <ctime>
 9 #include <vector>
10 #include <queue>
11 #include <map>
12 #include <set>
13 using namespace std;
14 typedef long long LL;
15 const int inf = (1<<30);
16 LL n,m,X,Y,L;
17 LL a,b;
18 LL GCD,ans;
19 
20 inline int getint()
21 {
22     int w=0,q=0; char c=getchar();
23     while((c<‘0‘ || c>‘9‘) && c!=‘-‘) c=getchar(); if(c==‘-‘) q=1,c=getchar(); 
24     while (c>=‘0‘ && c<=‘9‘) w=w*10+c-‘0‘, c=getchar(); return q ? -w : w;
25 }
26 
27 inline LL extend_gcd(LL aa,LL bb,LL &x,LL &y){
28     if(bb==0) {
29     x=1; y=0;
30     return aa;
31     }
32     LL cun=extend_gcd(bb,aa%bb,x,y),lin=x;
33     x=y; y=lin-(aa/bb)*y;
34     return cun;
35 }
36 
37 inline void work(){
38     X=getint(); Y=getint(); m=getint(); n=getint(); L=getint();
39     if(n==m) { printf("Impossible"); return ; }//不可能相遇
40     GCD=extend_gcd(n-m,L,a,b);
41     LL you=X-Y;
42     if(you%GCD!=0) { printf("Impossible"); return ; }//无解
43     L/=GCD; you/=GCD;//我们希望L的系数最小
44     ans=you*a; ans%=L; ans+=L; ans%=L;
45     printf("%lld",ans);
46 }
47 
48 int main()
49 {
50     work();
51     return 0;
52 }