bzoj1009: [HNOI2008]GT考试

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<iostream>

using namespace std;

void setIO(const string& s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
template<typename Q> Q read(Q& x) {
static char c, f;
for(f = 0; c = getchar(), !isdigit(c); ) if(c == '-') f = 1;
for(x = 0; isdigit(c); c = getchar()) x = x * 10 + c - '0';
if(f) x = -x;
return x;
}
template<typename Q> Q read() {
static Q x; read(x); return x;
}

const int N = 20 + 5;

int n, m, p;

template<typename Q> void addit(Q& x, const Q& y) {
if((x += y) >= p) x -= p;
}

struct Matrix {
int da

;

void clear() {
memset(da, 0, sizeof da);
}

Matrix operator * (const Matrix& b) const {
static Matrix c;
c.clear();
for(int i = 0; i < m; i++) {
for(int j = 0; j < m; j++){
for(int k = 0; k < m; k++){
addit(c.da[i][j], da[i][k] * b.da[k][j] % p);
}
}
}
return c;
}
}A, B;

char s
;
int fail
;

void kmp() {
for(int j = 0, i = 2; i <= m; i++) {
while(j && s[i] != s[j+1]) j = fail[j];
if(s[i] == s[j+1]) j++;
fail[i] = j;
}
}

void getMatrixB() {
for(int i = 0; i < m; i++) {
for(int j = 0; j <= 9; j++) {
int k = i;
while(k && s[k+1] != j + '0') k = fail[k];
if(s[k+1] == j + '0') ++k;
++B.da[i][k];
}
}
}

Matrix qpow(Matrix a, int b) {
Matrix c = a;
for(b--; ; a = a * a) {
if(b & 1) c = c * a;
if(!(b >>= 1)) return c;
}
}

int main() {
#ifdef DEBUG
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif

scanf("%d%d%d", &n, &m, &p);
scanf("%s", s + 1);

kmp();
getMatrixB();
A.da[0][0] = 1;
B = qpow(B, n);
A = A * B;
int res = 0;
for(int i = 0; i < m; i++) {
addit(res, B.da[0][i]);
}
printf("%d\n", res);

return 0;
}