HDU 3065 病毒侵袭持续中（AC自动机）题解

题意：要你找到主串中每个模式串的个数。

思路：题目都没说是多组数据，结果没while(~)直接WA了，和上一题差不多，可以用map或者开个数组储存。指针要记得回收内存，不然MLE。

#include<cstdio>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<cstring>
#include<string>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#define ll long long
const int maxn = 5000000+5;
const int maxm = 100000+5;
const int MOD = 1e7;
const int INF = 0x3f3f3f3f;
const int kind = 130;
const char baset = 0;
using namespace std;
struct Trie{
    Trie *next[kind];
    Trie *fail; //失配值
    int sum;    //以此为单词结尾的个数
    int id;
    Trie(){
        sum = 0;
        memset(next,NULL,sizeof(next));
        fail = NULL;
        id = 0;
    }
};
Trie *root;
queue<Trie *> Q;
int head,tail,record[1005];
//map<int,int> record;
void Insert(char *s,int id){
    Trie *p = root;
    for(int i = 0;s[i];i++){
        int x = s[i] - baset;
        if(p ->next[x] == NULL){
            p ->next[x] = new Trie();
        }
        p = p ->next[x];
    }
    p ->sum++;
    p ->id = id;
}
void del(Trie *p){
    if(p == NULL) return;
    for(int i = 0;i < kind;i++){
        if(p ->next[i])
            del(p ->next[i]);
    }
    delete p;
}
void buildFail(){
    while(!Q.empty()) Q.pop();
    Q.push(root);
    Trie *p,*temp;
    while(!Q.empty()){
        temp = Q.front();
        Q.pop();
        for(int i = 0;i < kind;i++){
            if(temp ->next[i]){
                if(temp == root){
                    temp ->next[i] ->fail = root;
                }
                else{
                    p = temp ->fail;
                    while(p){
                        if(p ->next[i]){
                            temp ->next[i] ->fail = p ->next[i];
                            break;
                        }
                        p = p ->fail;
                    }
                    if(p == NULL) temp ->next[i] ->fail = root;
                }
                Q.push(temp ->next[i]);
            }
        }
    }
}
void ac_automation(char *ch){
    Trie *p = root;
    int len = strlen(ch);
    for(int i = 0;i < len;i++){
        int x = ch[i] - baset;
        while(!p ->next[x] && p != root)
            p = p ->fail;
        p = p ->next[x];
        if(!p) p = root;
        Trie *temp = p;
        while(temp != root){
            if(temp ->id > 0) record[temp ->id]++;
            temp = temp ->fail;
        }
    }
}
char ch[1005][55];
char s[2000005];
int main(){
    int n,m,x;
    while(scanf("%d",&n) != EOF){
        root = new Trie();
        memset(record,0,sizeof(record));
        for(int i = 1;i <= n;i++){
            scanf("%s",ch[i]);
            Insert(ch[i],i);
        }
        buildFail();
        scanf("%s",s);
        ac_automation(s);
        for(int i = 1;i <= n;i++){
            if(record[i] > 0)
                printf("%s: %d\n",ch[i],record[i]);
        }
        del(root);
    }
    return 0;
}