【luogu P1962 斐波那契数列】 题解

题目链接：https://www.luogu.org/problemnew/show/P1962

给你篇dalao的blog自己看吧，把矩阵快速幂的板子一改就OK

 #include <algorithm>
 #include <iostream>
 #include <cstring>
 #include <cstdio>
 using namespace std;
 struct Matrix{
     long long m[][];
 }A,E,ans;
 long long n,k, mod = ;
 Matrix mul(Matrix A,Matrix B)
 {
     Matrix C;
     for(int i = ; i <= ; i++)
         for(int j = ; j <= ; j++)
         {
             C.m[i][j] = ;
             for(int k = ; k <= ; k++)
                 C.m[i][j] = (C.m[i][j]+(A.m[i][k]*B.m[k][j]))%mod;
         }
     return C;
 }
 Matrix fast(Matrix A, long long k)
 {
     Matrix S = E;
     while(k)
     {
         if(k&) S = mul(S,A);
         A = mul(A,A);
         k = k>>;
     }
     return S;
 }
 int main(){

     scanf("%lld",&k);

     E.m[][] = ;
     E.m[][] = ;
     A.m[][] = ;
     A.m[][] = ;
     A.m[][] = ;
     ans = fast(A,k);

     printf("%lld ",(ans.m[][])%mod);
     return ;
 }