BZOJ3122: [Sdoi2013]随机数生成器

#include<cstdio>
#include<iostream>
#include<cstring>
#include<map>
#include<cmath>
using namespace std;
#define ll long long
ll ex_gcd(ll &x,ll &y,ll a,ll b)
{
if(b==0){x=1;y=0;return a;}
ll c=ex_gcd(x,y,b,a%b),tp=x;
x=y;y=tp-a/b*y;
return c;
}
ll p,T;
char c;
inline void read(ll &a)
{a=0;do c=getchar();while(c<'0'||c>'9');while(c<='9'&&c>='0')a=(a<<3)+(a<<1)+c-'0',c=getchar();}

map<ll,ll>S;

int main()
{

freopen("std.in","r",stdin);
freopen("self.out","w",stdout);
read(T);
while(T--)
{
ll p,i,a,b,x1,t;
ll xa,xp;
read(p),read(a),read(b),read(x1),read(t);
a%=p;
if(t>=p){puts("-1");continue;}
if(x1==t){puts("1");continue;}
if(a==1)
{
if(b==0)
puts("-1");
else
{
ll xi,yq;
ll c=ex_gcd(xi,yq,b,p);
if((t-x1)%c||c!=1)puts("-1");
else printf("%lld\n",1+((xi*(t-x1)/c)%p+p)%p);
}
continue;
}
if(a==0)
{
if(t==b)puts("2");
else puts("-1");continue;
}
ex_gcd(xa,xp,a-1,p);
S.clear();
xa%=p;
xa+=p;
xa%=p;
ll xb;
ex_gcd(xb,xp,x1+b*xa,p);
xb%=p;
xb+=p;
xb%=p;
ll right=((t+b*xa)%p)*xb;
right%=p;
right+=p;
right%=p;
ll size=sqrt(p)+1;
ll tp=right;
for(i=0;i<=size;i++,tp*=a,tp%=p)
S[tp]=i+1;
tp=a;
ll left=1,ab=1;
for(i=1;i<=size;i++)ab*=a,ab%=p;
left=ab;
for(i=1;i<=1+p/size;i++,left*=ab,left%=p)
if(S[left]){
printf("%lld\n",i*size-S[left]+2);goto asd;}
puts("-1");
asd:;
}
return 0;
}