hdu 1757 A Simple Math Problem 矩阵优化+快速幂

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int  n=10;
int kt,m;

struct Matrix
{
    int mp[n][n];
};

Matrix mul(Matrix a,Matrix b)
{
    int i,j,k;
    Matrix c;

    for(i=0; i<10; i++)
        for(j=0; j<10; j++)
        {
            c.mp[i][j]=0;
            for(k=0; k<10; k++)
            {
                c.mp[i][j]=(c.mp[i][j]+a.mp[i][k]*b.mp[k][j])%m;
            }
        }
    return c;
}

Matrix pow(Matrix t,int x)
{
    if(x==1) return t;
    Matrix c;
    c=pow(t,x/2);
    c=mul(c,c);
    if(x&1)
        return mul(c,t);
    else
        return c;
}

int main()
{
    int i,j,ans;
    Matrix a,t;
    while(~scanf("%d%d",&kt,&m))
    {
        for(i=0;i<n;i++)
            scanf("%d",&a.mp[0][i]);
        if(kt<10)
        {
            printf("%d
",kt%m);
            continue;
        }

        for(i=1;i<n;i++)
            for(j=0;j<n;j++)
        {
            if(i==j+1) a.mp[i][j]=1;
            else a.mp[i][j]=0;
        }
        t=pow(a,kt-9);
        for(i=0,ans=0;i<n;i++)
        {
            //printf("%d
",ans);
            ans=(ans+t.mp[0][i]*(n-i-1))%m;
        }
        printf("%d
",ans);
    }
    return 0;
}