洛谷P4591 [TJOI2018]碱基序列 【KMP + dp】

题目链接

洛谷P4591

题解

设\(f[i][j]\)表示前\(i\)个串匹配到位置\(j\)的方案数，匹配一下第\(i\)个串进行转移即可

本来写了\(hash\)，发现没过，又写了一个\(KMP\)，依旧\(WA\)，无奈去翻题解，竟然要取模??!!

题面怎么不讲啊，，

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<map>
#define Redge(u) for (int k = h[u],to; k; k = ed[k].nxt)
#define REP(i,n) for (int i = 1; i <= (n); i++)
#define mp(a,b) make_pair<int,int>(a,b)
#define cls(s) memset(s,0,sizeof(s))
#define cp pair<int,int>
#define LL long long int
using namespace std;
const int maxn = 10005,maxm = 100005,INF = 1000000000,Mod = 1000000007;
inline int read(){
	int out = 0,flag = 1; char c = getchar();
	while (c < 48 || c > 57){if (c == '-') flag = -1; c = getchar();}
	while (c >= 48 && c <= 57){out = (out << 3) + (out << 1) + c - 48; c = getchar();}
	return out * flag;
}
char s[maxn],P[maxn];
int len,K,m,nxt[maxn];
LL f[105][maxn];
void getf(){
	nxt[1] = 0;
	for (int i = 1,j = 0; i < m; i++){
		while (j && P[i + 1] != P[j + 1]) j = nxt[j];
		if (P[i + 1] == P[j + 1]) nxt[i + 1] = ++j;
	}
}
int main(){
	K = read();
	scanf("%s",s + 1); len = strlen(s + 1);
	for (int i = 0; i <= len; i++) f[0][i] = 1;
	for (int i = 1; i <= K; i++){
		int a = read();
		while (a--){
			scanf("%s",P + 1);
			m = strlen(P + 1);
			getf();
			int j = 0;
			for (int k = 1; k <= len; k++){
				while (j && P[j + 1] != s[k]) j = nxt[j];
				if (P[j + 1] == s[k]) j++;
				if (j == m){
					f[i][k] = (f[i][k] + f[i - 1][k - m]) % Mod;
				}
			}
		}
	}
	LL ans = 0;
	for (int i = 0; i <= len; i++) ans = (ans + f[K][i]) % Mod;
	printf("%lld\n",ans);
	return 0;
}