递推+矩阵快速幂 HDU 2065

#include <iostream>
#include <cstring>
#include <cstdio>

using namespace std;

//矩阵大小上限
const int SIZ=100;
int MOD=100;

//矩阵大小为n*m，初始化全部为0
struct mat
{
    int n,m;
    int ar[SIZ][SIZ];
    mat()
    {
        memset(ar,0,sizeof(ar));
        n=m=SIZ;
    };
};

//矩阵乘法
mat operator *(mat a,mat b)
{
    mat c;
    c=mat();
    c.n=a.n;
    c.m=b.m;
    for(int i=1;i<=a.n;i++)
        for(int j=1;j<=b.n;j++)
            if(a.ar[i][j]!=0)
            for(int k=1;k<=a.m;k++)
            {
                c.ar[i][k]+=(a.ar[i][j]*b.ar[j][k])%MOD;
                c.ar[i][k]%=MOD;
            }
    return c;
}

//矩阵快速幂
mat operator ^(mat a,long long k)
{
    mat c;
    c=mat();
    c.n=a.n;
    c.m=a.m;
    for(int i=1;i<=a.n;i++)
        c.ar[i][i]=1;
    while(k)
    {
        if(k&1)
            c=c*a;
        a=a*a;
        k/=2;
    }
    return c;
}

int main()
{
    int T;
    while(scanf("%d",&T)!=EOF)
    {
        if(T==0)
            break;
        for(int l=1;l<=T;l++)
        {
            long long n;
            mat a;
            a.m=a.n=4;
            for(int i=1;i<=4;i++)
            {
                for(int j=1;j<=4;j++)
                {
                    a.ar[i][j]=1;
                    if(i==j)
                        a.ar[i][j]=2;
                    if(i+j==5)
                        a.ar[i][j]=0;
                }
            }
            scanf("%I64d",&n);
            mat b=a^n;
            int ans=b.ar[1][1];
            cout<<"Case "<<l<<": "<<ans<<endl;
        }
        cout<<endl;
    }
    return 0;
}