AC自动机学习小记 Hdu 2222 Keywords Search (模板)

学习链接：http://wenku.baidu.com/view/4cf3374769eae009591bec05.html

题目集锦及解题报告：

AC自动机专题-将狼踩尽 19891101

AC自动机专题-yefeng1627

AC自动机专题-E_star

以下代码参考了以上博文。

题意:求给定n个模式串在主串中出现了几个。(每一个模式串只被记录一次)

三种实现，指针版本最快。

#include <cstdio>#include <cstring>const int MAXPT=500007;   //最大节点数const int size=26;     //子节点数const char start='a';  //子节点标号对应关系 class Ac_Automat{private:struct Node{Node *fail;Node *next[size];int cnt;    //各种用途:计数,标号等bool flag;   //是否为单词结束void newnode () //生成节点{fail=NULL;for (int i=0;i<size;i++)next[i]=NULL;cnt=0;flag=false;}};Node *q[MAXPT],H[MAXPT],*root;int fr,tl,t;public:void Init (){fr = tl = 0;t = 0;H[t].newnode();root = &H[t++];}void Insert (char *s){int len = strlen(s);Node *p = root;for (int i=0;i<len;i++){int k = s[i] - start;if (p->next[k] == NULL){H[t].newnode();p->next[k] = &H[t++];}p = p->next[k];}p->cnt++;p->flag=true;}void Build (){root->fail = NULL;q[tl] = root;while (fr <= tl){Node *tmp = q[fr++];Node *p = NULL;for (int i=0;i<size;i++) if (tmp->next[i]){if (tmp == root)tmp->next[i]->fail = root;else{p = tmp->fail;while (p != NULL){if (p->next[i]){tmp->next[i]->fail = p->next[i];break;}p = p->fail;}if (p == NULL) tmp->next[i]->fail = root;}q[++tl] = tmp->next[i];}}}int Query (char *s){int res = 0;Node *p = root;int len = strlen(s);for (int i=0;i<len;i++){int k = s[i] - start;while (p->next[k] == NULL && p != root)p = p->fail;p = p->next[k];if (p == NULL) p = root;Node *tmp = p;while (tmp != root && tmp->cnt != -1)  //随查询要求不同而修改{res += tmp->cnt;tmp->cnt = - 1;tmp = tmp->fail;}}return res;}}ac;char str[1000005],s[55];int main (){#ifdef ONLINE_JUDGE#elsefreopen("read.txt","r",stdin);#endifint T,i,n;scanf("%d",&T);while (T--){scanf("%d",&n);ac.Init();for (i=1;i<=n;i++)scanf("%s",s),ac.Insert(s);scanf("%s",str);ac.Build();printf("%d\n",ac.Query(str));}return 0;}

#include <cstdio>#include <set>#include <algorithm>#include <map>#include <cstring>#include <queue>using namespace std;const int MAXPT = 500007;  //MAXPT = StringNumber * StringLengthconst int size = 26;const char start='a'; class ACAutomaton{private:int chd[MAXPT][size];int val[MAXPT];//记录题目给的关键数据int fail[MAXPT];//fail指针int Q[MAXPT];//队列,用于广度优先计算fail指针int ID[128];//字母对应的Iint sz;//已使用节点个数public:    void Set ()//初始化,计算字母对应的儿子ID,如:'a'->0 ... 'z'->25{fail[0]=0;for (int i=0;i<size;i++)ID[i+start] = i;}    void Init (){Set();memset(chd[0],0,sizeof(chd[0]));sz = 1;}    void Insert (char *a){int p=0;for (; *a ; a++){int c = ID[*a];if (!chd[p][c]){memset(chd[sz] , 0 , sizeof(chd[sz]));val[sz]=0;chd[p][c] = sz++;}p = chd[p][c];}val[p]++;}void Build (){int *s=Q, *e=Q,i;for (i=0;i<size;i++)if (chd[0][i]){fail[ chd[0][i] ] = 0;*e ++ = chd[0][i];            }while (s != e){int u = *s++;for (i=0;i<size;i++){int &v = chd[u][i];if (v){*e ++ = v;fail[v] = chd[ fail[u] ][i];}elsev = chd[ fail[u] ][i];}}}int Query (char *s){int p=0,k,ans=0;for (; *s; s++){k = ID[*s];while (!chd[p][k] && p!=0)p = fail[p];p = chd[p][k];int rt = p;while (rt != 0 && val[rt] != -1){ans += val[rt];val[rt] = -1;rt = fail[rt];}}return ans;}}ac;char str[1000005],s[55];int main (){#ifdef ONLINE_JUDGE#elsefreopen("read.txt","r",stdin);#endifint T,i,n;scanf("%d",&T);while (T--){scanf("%d",&n);ac.Init();for (i=1;i<=n;i++)scanf("%s",s),ac.Insert(s);scanf("%s",str);ac.Build();printf("%d\n",ac.Query(str));}return 0;}

#include <iostream>#include <queue>#include <string.h>using namespace std;const int size=26;const int N=250005;struct Node{int next[size],pre,leafn,flag;void Init (){memset(next,0,sizeof(next));pre=-1,leafn=0,flag=0;}}a[N];int e,n,root;char str[1000005],s[55];void Insert (char str[],int id){int p=root;for (int i=0;str[i];i++){if (a[p].next[str[i]-'a']==0)a[p].next[str[i]-'a']=++e;p=a[p].next[str[i]-'a'];}a[p].leafn++;}void Build_DFA (){int i,p,q,k;queue<int> Q;for (i=0;i<size;i++) a[0].next[i]=1;a[0].pre=0,a[1].pre=0;Q.push(1);while (!Q.empty()){p=Q.front();Q.pop();for (i=0;i<size;i++) if (a[p].next[i]){q=a[p].next[i];k=a[p].pre;while (k!=-1)if (a[k].next[i]) {a[q].pre=a[k].next[i];break;}else k=a[k].pre;Q.push(q);}}}int Query (char str[]){int ans=0;int p=root,pre,k;for (int i=0;str[i];i++){k=str[i]-'a';while (p>=1)if (a[p].next[k]){p=a[p].next[k];pre=p;while (pre>=1 && a[pre].flag==0){a[pre].flag=1;ans+=a[pre].leafn;pre=a[pre].pre;}break;}else p=a[p].pre;if (p<1) p=1;}return ans;}int main (){#ifdef ONLINE_JUDGE#elsefreopen("read.txt","r",stdin);#endifint T,i;scanf("%d",&T);while (T--){scanf("%d",&n);root=e=1;for (i=0;i<N;i++)a[i].Init();for (i=1;i<=n;i++)scanf("%s",s),Insert(s,i);scanf("%s",str);Build_DFA();printf("%d\n",Query(str));}return 0;}