poj3070(矩阵乘法求fib)

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

const int mod=10000;

void mul(int f[2],int a[2][2]){
     int c[2];
     memset(c,0,sizeof(c));
     for (int i=0;i<2;i++){
        for (int j=0;j<2;j++){
            c[i]=(c[i]+f[j]*a[i][j])%mod;
        }
     }
     memcpy(f,c,sizeof(c));
}

void mull(int a[2][2]){
     int c[2][2];
     memset(c,0,sizeof(c));
     for (int i=0;i<2;i++){
        for (int j=0;j<2;j++){
            for (int k=0;k<2;k++){
                c[i][j]=(c[i][j]+a[i][k]*a[k][j])%mod;
            }
        }
     }
     memcpy(a,c,sizeof(c));
}

int main(){
    int n;
    while(scanf("%d",&n)&&n!=-1){
        int f[2]={0,1};
        int a[2][2]={{0,1},{1,1}};
        for (;n;n>>=1){
            if(n&1) mul(f,a);
            mull(a);
        }
        printf("%d\n",f[0]);
    }
return 0;
}