C++-POJ3070-Fibonacci-[矩阵乘法][快速幂]

#include <cstdio>
struct Matrix{int a[5][5];};
const int N=2,MOD=1e4;
Matrix A,B,O,I;
Matrix Mul(Matrix A,Matrix B){
    Matrix C=O;
    for(int i=1;i<=N;i++)
        for(int j=1;j<=N;j++)
            for(int k=1;k<=N;k++)
                C.a[i][j]=(C.a[i][j]+A.a[i][k]*B.a[k][j])%MOD;
    return C;
}
Matrix Pow(Matrix A,int n){
    Matrix B=I;
    for(;n;n>>=1,A=Mul(A,A))if(n&1)B=Mul(B,A);
    return B;
}
int main(){
    for(int i=1;i<=2;i++)for(int j=1;j<=2;j++)O.a[i][j]=0,I.a[i][j]=(i==j);
    A.a[1][1]=0,A.a[1][2]=1;
    A.a[2][1]=1,A.a[2][2]=1;
    int n;
    while(scanf("%d",&n)){
        if(n==-1)break;
        B=Pow(A,n+1),printf("%d
",B.a[1][1]);
    } 
    return 0;
}