（转载）HDU4565

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <algorithm>
 5 #include<cmath>
 6 #include<sstream>
 7 #include<string>
 8 using namespace std;
 9  __int64 b,k,n,mod;
10 struct matrix
11 {
12     __int64 m[2][2];
13 };
14 matrix a,per,s,ans;
15 void init()//初始化操作
16 {
17 
18     s.m[0][0]=((2*((k%mod)*(k%mod))%mod)%mod+(2*b)%mod)%mod;
19     s.m[0][1]=(2*(k%mod))%mod;
20     s.m[1][0]=0;
21     s.m[1][1]=0;
22 
23     a.m[0][0]=(2*(k%mod))%mod;
24     a.m[0][1]=1;
25     a.m[1][0]=(((b%mod)-((k%mod)*(k%mod))%mod)+mod)%mod;
26     a.m[1][1]=0;
27 }
28 matrix mul(matrix x,matrix y)
29 {
30     matrix temp;
31     memset(temp.m,0,sizeof(temp.m));
32     for(int i=0;i<2;i++)
33         for(int j=0;j<2;j++)
34         for(int k=0;k<2;k++)
35         temp.m[i][j]=(temp.m[i][j]+x.m[i][k]*y.m[k][j])%mod;
36     return temp;
37 }
38 matrix mpow(matrix A,__int64 n)
39 {
40     matrix B;
41     memset(B.m,0,sizeof(B.m));
42     for(int i=0;i<2;i++)
43         B.m[i][i]=1;
44     while(n>0)
45     {
46         if(n&1)
47             B=mul(B,A);
48         A=mul(A,A);
49         n>>=1;
50     }
51     return B;
52 }
53 int main()
54 {
55 
56   while(~scanf("%I64d%I64d%I64d%I64d",&k,&b,&n,&mod))
57     {
58         init();
59         if(n==1)
60         {
61             cout<<(2*(k%mod))%mod<<endl;
62             continue;
63         }
64         else if(n==2)
65         {
66             cout<<((2*(k%mod)*(k%mod))%mod+(2*(b%mod))%mod)%mod<<endl;
67             continue;
68         }
69         else
70         {
71             ans=mpow(a,n-2);
72             ans=mul(s,ans);
73             cout<<ans.m[0][0]<<endl;
74         }
75     }
76     return 0;
77 }