hdu 4758 (AC自动机)

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<vector>
#include <set>
#include <queue>
#define ll long long
#define ld long double
#define lson l,m,rt<<1
#define pi acos(-1)
#define rson m+1,r,rt<<1|1
#define fo(i,l,r) for(int i = l;i <= r;i++)
#define fd(i,l,r) for(int i = r;i >= l;i--)
#define mem(x) memset(x,0,sizeof(x))
#define eps 1e-8
using namespace std;
const int maxn = 250,maxs = 5;
const ll inf = 1e9;
const ll mod = 1000000007;
ll read() {
    ll x=0,f=1;
    char ch=getchar();
    while(!(ch>=‘0‘&&ch<=‘9‘)) {
        if(ch==‘-‘)f=-1;
        ch=getchar();
    };
    while(ch>=‘0‘&&ch<=‘9‘) {
        x=x*10+(ch-‘0‘);
        ch=getchar();
    };
    return x*f;
}
struct Trie{
    int nxt[maxn][maxs],fail[maxn],end[maxn];
    int root,L;
    int newnode(){
        for(int i = 0;i < maxs;i++)
            nxt[L][i] = -1;
        end[L++]=0;
        return L-1;
    }
    void init(){
        L = 0;
        root = newnode();
    }
    void insert(char buf[],int id){
        int len = strlen(buf);
        int now = root;
        for(int i = 0;i < len;i++){
            if(buf[i]==‘R‘)buf[i]=0;
            else buf[i]=1;
            if(nxt[now][buf[i]]==-1)
                nxt[now][buf[i]] = newnode();
            now = nxt[now][buf[i]];
        }
        end[now]|=id;
    }
    void build(){
        queue<int> Q;
        fail[root] = root;
        for(int i = 0;i < maxs;i++) {
            if (nxt[root][i] == -1) {
                nxt[root][i] = root;
            } else {
                fail[nxt[root][i]] = root;
                Q.push((nxt[root][i]));
            }
        }
        while(!Q.empty()){
            int now = Q.front();
            Q.pop();
            end[now] |= end[fail[now]];
            for(int i = 0;i < maxs;i++){
                if(nxt[now][i]==-1) {
                    nxt[now][i] = nxt[fail[now]][i];
                }else{
                    fail[nxt[now][i]] = nxt[fail[now]][i];
                    Q.push(nxt[now][i]);
                }
            }
        }
    }
}ac;
int n,m;
char s[105];
int dp[105][105][250][4];
void gao(){
    fo(i,0,n){
        fo(j,0,m){
            fo(k,0,ac.L){
                fo(t,0,3) {
                    dp[i][j][k][t] = 0;
                }
            }
        }
    }
    dp[0][0][0][0]=1;
    fo(i,0,n){
        fo(j,0,m){
            fo(k,0,ac.L-1){
                fo(t,0,3){
                    dp[i][j+1][ac.nxt[k][0]][t|ac.end[ac.nxt[k][0]]] += dp[i][j][k][t];
                    dp[i+1][j][ac.nxt[k][1]][t|ac.end[ac.nxt[k][1]]] += dp[i][j][k][t];
                    dp[i][j+1][ac.nxt[k][0]][t|ac.end[ac.nxt[k][0]]] %= mod;
                    dp[i+1][j][ac.nxt[k][1]][t|ac.end[ac.nxt[k][1]]] %= mod;
                }
            }
        }
    }
    ll ans = 0;
    fo(i,0,ac.L-1){
        ans = (ans + dp[n][m][i][3]) % mod;
    }
    printf("%lld\n",ans);
}
int main() {
    int T=read();
    while(T--){
        ac.init();
        m=read();n=read();
        fo(i,1,2){
            scanf("%s",s);
            ac.insert(s,i);
        }
        ac.build();
        gao();
    }
    return 0;
}