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;

}