hdu------(1757)A Simple Math Problem(简单矩阵快速幂)

时间:2024-04-07 20:05:49

A Simple Math Problem

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 2791    Accepted Submission(s): 1659

Problem Description
Lele now is thinking about a simple function f(x).

If x < 10 f(x) = x.
If x >= 10 f(x) = a0 * f(x-1) + a1 * f(x-2) + a2 * f(x-3) + …… + a9 * f(x-10);
And ai(0<=i<=9) can only be 0 or 1 .

Now, I will give a0 ~ a9 and two positive integers k and m ,and could you help Lele to caculate f(k)%m.

Input
The problem contains mutiple test cases.Please process to the end of file.
In each case, there will be two lines.
In the first line , there are two positive integers k and m. ( k<2*10^9 , m < 10^5 )
In the second line , there are ten integers represent a0 ~ a9.
Output
For each case, output f(k) % m in one line.
Sample Input
10 9999
1 1 1 1 1 1 1 1 1 1
20 500
1 0 1 0 1 0 1 0 1 0
Sample Output
45
104
Author
linle
Source
 代码:
 //#define LOCAL
#include<cstdio>
#include<cstring>
#define LL __int64
using namespace std;
const int maxn=;
LL k,m;
int aa[maxn],mat[maxn][maxn];
int ans[maxn][maxn]; void init()
{
for(int i=;i<;i++)
{
for(int j=;j<;j++)
{
if(i==)
mat[i][j]=aa[j];
else
if(i==j+)mat[i][j]=;
else mat[i][j]=;
if(i==j)
ans[i][j]=;
else ans[i][j]=;
}
}
} void Matrix(int a[][],int b[][])
{ int c[][];
for(int i=;i<;i++)
{
for(int j=;j<;j++)
{
c[i][j]=;
for(int k=;k<;k++)
{
c[i][j]=(c[i][j]+a[i][k]*b[k][j])%m;
}
}
}
for(int i=;i<;i++)
{
for(int j=;j<;j++)
{
a[i][j]=c[i][j];
}
}
} void pow(LL n)
{
while(n>)
{
if(n&) Matrix(ans,mat);
n>>=1L;
if(n==)break;
Matrix(mat,mat);
}
} int main()
{
#ifdef LOCAL
freopen("test.in","r",stdin);
#endif while(scanf("%I64d%I64d",&k,&m)!=EOF)
{
for(int i=;i<;i++)
scanf("%d",aa+i);
if(k<) printf("%I64d\n",k%m);
else
{
init();
pow(k-);
int res=;
for(int i=;i<;i++)
res=(res+(-i-)*ans[][i])%m;
printf("%d\n",res);
}
}
return ;
}