版权声明:https://blog.csdn.net/qq_41730082 https://blog.csdn.net/qq_41730082/article/details/86590014
题目链接
很多人用了Trie图去做了这道题,或许那个做法确实会快得多,但是,我却想到了在AC自动机上写了个DP,与2018四川省赛(第十届四川省ACM)那道题一样,甚至还要略微简单一些,这道题就敲出来了,它不用记录路径,直接输出最后的解即可,嗯……好题。嘤嘤嘤……
#include <iostream>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
#include <limits>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#define lowbit(x) ( x&(-x) )
#define pi 3.141592653589793
#define e 2.718281828459045
#define INF 0x3f3f3f3f
#define HalF (l + r)>>1
#define lsn rt<<1
#define rsn rt<<1|1
#define Lson lsn, l, mid
#define Rson rsn, mid+1, r
#define QL Lson, ql, qr
#define QR Rson, ql, qr
#define myself rt, l, r
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const int maxN = 3e5 + 7;
const int mod = 20071027;
int N, dp[maxN], lten;
char test[maxN], virus[105];
struct node
{
node *next[26];
node *fail, *las;
int sum, len;
node()
{
for(int i=0; i<26; i++) next[i] = NULL;
fail = NULL; las = NULL;
sum = len = 0;
}
};
node *root;
void update(char *s)
{
node *temp = root;
int len = (int)strlen(s);
for(int i=0; i<len; i++)
{
int x = s[i] - 'a';
if(temp->next[x] == NULL) temp->next[x] = new node();
temp = temp->next[x];
}
temp->sum = 1;
temp->len = len;
}
void build_fail()
{
queue<node *> Q;
Q.push(root);
node *temp, *p;
while(!Q.empty())
{
temp = Q.front(); Q.pop();
for(int i=0; i<26; i++)
{
if(temp->next[i])
{
if(temp == root) { temp->next[i]->fail = root; temp->next[i]->las = root; }
else
{
p = temp->fail;
while(p)
{
if(p->next[i]) { temp->next[i]->fail = p->next[i]; break; }
p = p->fail;
}
if(!p) { temp->next[i]->fail = root; temp->next[i]->las = root; }
else
{
if(p->next[i]->sum) temp->next[i]->las = p->next[i];
else temp->next[i]->las = p->next[i]->las;
}
}
Q.push(temp->next[i]);
}
}
}
}
void AC_auto() //对test的处理啦
{
node *p = root;
for(int i=1; i<=lten; i++)
{
int x = test[i] - 'a';
while(p!=root && !p->next[x]) p = p->fail;
p = p->next[x];
if(!p) p = root;
node *temp = p;
while(temp && temp != root)
{
if(temp->sum)
{
dp[i] += dp[i - temp->len];
if(dp[i] >= mod) dp[i] -= mod;
}
temp = temp->las;
}
}
}
inline void init()
{
lten = (int)strlen(test + 1);
dp[0] = 1;
for(int i=1; i<=lten; i++) dp[i] = 0;
root = (node *)malloc(sizeof(node));
for(int i=0; i<26; i++) root->next[i] = NULL;
root->fail = NULL; root->las = NULL;
root->sum = 0;
}
int main()
{
int Cas = 0;
while(scanf("%s", test + 1)!=EOF)
{
init();
scanf("%d", &N);
for(int i=1; i<=N; i++)
{
scanf("%s", virus);
update(virus);
}
build_fail();
AC_auto();
printf("Case %d: %d\n", ++Cas, dp[lten]);
}
return 0;
}