HDU-2243 考研路茫茫——单词情结(AC自动机)

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

# define LL long long
# define ULL unsigned long long

struct Matrix
{
int n;
ULL ele[35][35];
Matrix(int _n):n(_n){
for(int i=0;i<n;++i) for(int j=0;j<n;++j)
ele[i][j]=0;
}
};
int ch[35][26];
int fail[35],cnt;
bool word[35];

void init()
{
cnt=0;
memset(ch,-1,sizeof(ch));
memset(word,false,sizeof(word));
}

int idx(char c)
{
return c-'a';
}

void insert(char *s)
{
int n=strlen(s);
int r=0;
for(int i=0;i<n;++i){
int c=idx(s[i]);
if(ch[r][c]==-1) ch[r][c]=++cnt;
r=ch[r][c];
}
word[r]=true;
}

void getFail()
{
queue<int>q;
fail[0]=0;
for(int i=0;i<26;++i){
if(ch[0][i]==-1){
ch[0][i]=0;
}else{
fail[ch[0][i]]=0;
q.push(ch[0][i]);
}
}
while(!q.empty())
{
int u=q.front();
q.pop();
if(word[fail[u]]) word[u]=true;
for(int i=0;i<26;++i){
if(ch[u][i]==-1)
ch[u][i]=ch[fail[u]][i];
else{
fail[ch[u][i]]=ch[fail[u]][i];
q.push(ch[u][i]);
}
}
}
}

Matrix getMatrix()
{
Matrix mat(cnt+1);
for(int i=0;i<mat.n;++i)
for(int j=0;j<26;++j) if(!word[ch[i][j]])
++mat.ele[i][ch[i][j]];
++mat.n;
for(int i=0;i<mat.n;++i){
mat.ele[mat.n-1][i]=0;
mat.ele[i][mat.n-1]=1;
}
return mat;
}

Matrix mul(Matrix a,Matrix b)
{
Matrix c(a.n);
for(int i=0;i<c.n;++i) for(int j=0;j<c.n;++j)
for(int k=0;k<c.n;++k) c.ele[i][j]+=a.ele[i][k]*b.ele[k][j];
return c;
}

Matrix myPow(Matrix a,LL k)
{
Matrix mat(a.n);
for(int i=0;i<mat.n;++i) mat.ele[i][i]=1;
while(k>0){
if(k&1) mat=mul(mat,a);
a=mul(a,a);
k>>=1;
}
return mat;
}

ULL getSum(LL x)
{
Matrix mat(2);
mat.ele[0][0]=26;
mat.ele[0][1]=1;
mat.ele[1][0]=0;
mat.ele[1][1]=1;
mat=myPow(mat,x);
return mat.ele[0][1];
}

char prefix[8];

int main()
{
int n;
LL L;
while(~scanf("%d%lld",&n,&L))
{
init();
for(int i=0;i<n;++i){
scanf("%s",prefix);
insert(prefix);
}
getFail();
Matrix mat=getMatrix();
mat=myPow(mat,L+1);
ULL ans1=mat.ele[0][mat.n-1];
ULL ans2=getSum(L+1);
cout<<ans2-ans1<<endl;
}
return 0;
}