Another kind of Fibonacci
http://acm.hdu.edu.cn/showproblem.php?pid=3306
題解:
考慮1*4 的矩陣【s[n-2],a[n-1]^2,a[n-2]^2,a[n-1]*a[n-2]】
我們需要找到一個4×4的矩陣A,使得它乘以A得到1×4的矩陣
【s[n-1],a[n]^2,a[n-1]^2,a[n]*a[n-1]】
即:【s[n-2],a[n-1]^2,a[n-2]^2,a[n-1]*a[n-2]】* A = 【s[n-1],a[n]^2,a[n-1]^2,a[n]*a[n-1]】
= 【s[n-2]+a[n-1]^2 , x^2 * a[n-1]^2 + y^2 * a[n-2]^2 + 2*x*y*a[n-1]*a[n-2] ,a[n-1]^2 , x*a[n-1]^2 + y*a[n-2]a[n-1]】
可以構造矩陣A為:
1???? 0??? 0??? 0
1??? x^2?? 1??? x
0??? y^2?? 0??? 0
0??? 2xy?? 0??? y
故:【S[0],a[1]^2,a[0]^2,a[1]*a[0]】 * A^(n-1) = 【s[n-1],a[n]^2,a[n-1]^2,a[n]*a[n-1]】
所以:【S[0],a[1]^2,a[0]^2,a[1]*a[0]】 * A^(n) = 【s[n],a[n+1]^2,a[n]^2,a[n+1]*a[n]】
若A = (B * C ) 則AT?= ( B * C )T?= CT?* BT
故
參考文章:?矩陣乘積? ??矩陣快速冪? ?矩陣構造方法? ?
/* *@Author: STZG *@Language: C++ */ #include <bits/stdc++.h> #include<iostream> #include<algorithm> #include<cstdlib> #include<cstring> #include<cstdio> #include<string> #include<vector> #include<bitset> #include<queue> #include<deque> #include<stack> #include<cmath> #include<list> #include<map> #include<set> //#define DEBUG #define RI register int #define endl "\n" using namespace std; typedef long long ll; //typedef __int128 lll; const int N=10+10; const int M=100000+10; const int MOD=1e9+7; const double PI = acos(-1.0); const double EXP = 1E-8; const int INF = 0x3f3f3f3f; int t,n,m,k,p,l,r,u,v,x,y; int ans,cnt,flag,temp,sum; int s[N][N]; int b[N][N]; int a[N][N]; char str; struct node{}; void Matrix(ll a[N][N],ll b[N][N]){ll c[N][N];memset(c,0,sizeof(c));for(int i=0;i<4;i++){for(int j=0;j<4;j++){for(int k=0;k<4;k++){c[i][j]=(c[i][j]+a[i][k]*b[k][j])%10007;}}}for(int i=0;i<4;i++){for(int j=0;j<4;j++){a[i][j]=c[i][j];}} } ll power(int A,int B,int k){ll b[N][N]={{1,0,0,0},{1,A*A,1,A},{0,B*B,0,0},{0,2*A*B,0,B}};ll a[N][N]={{1,1,1,1},{0,0,0,0},{0,0,0,0},{0,0,0,0}};while(k){if(k&1)Matrix(a,b);Matrix(b,b);k>>=1;}return a[0][0]; } int main() { #ifdef DEBUGfreopen("input.in", "r", stdin);//freopen("output.out", "w", stdout); #endif//ios::sync_with_stdio(false);//cin.tie(0);//cout.tie(0);//scanf("%d",&t);while(~scanf("%d%d%d",&n,&x,&y)){cout<<power(x%10007,y%10007,n)<<endl;}#ifdef DEBUGprintf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC); #endif//cout << "Hello world!" << endl;return 0; }?
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