有很多种构造方法
我的构造方法是
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#include <bits/stdc++.h>
#define ll long long
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define ROF(i,a,b) for(int i=a;i>=b;i--)
using namespace std;
const int mod=1e9+7;
struct matrix{
ll m[2][2];
}ans,bs;
ll m,a,b,x;
matrix multi(matrix a,matrix b){
matrix c;
for(ll i = 0; i < 2; i++){
for(ll j = 0; j< 2; j++){
c.m[i][j] = 0;
for(ll k = 0; k< 2; k++){
c.m[i][j] = (c.m[i][j]+a.m[i][k]*b.m[k][j]%mod)%mod;
}
}
}
return c;
}
ll fast_mod(ll n){
bs.m[0][0]=a;
bs.m[1][1]=bs.m[0][1]=1;
ans.m[0][0]=ans.m[1][1]=1;
bs.m[1][0]=ans.m[0][1]=ans.m[1][0]=0;
while(n){
if(n&1)
ans=multi(ans,bs);
bs=multi(bs,bs);
n>>=1;
}
return (ans.m[0][0]*x%mod+ans.m[0][1]*b%mod)%mod;
}
int main()
{
while(~scanf("%I64d%I64d%I64d%I64d",&a,&b,&m,&x)){
printf("%I64d\n",fast_mod(m));
}
return 0;
}