HDU 2222 Keywords Search（AC自动机模板题）

#include <stdio.h>
#include <string.h>
#include <queue>
using namespace std;
const int MAXN = 250010;
const int K = 26;

struct Trie{
        int wordEnd;
        int fail;
        int next[K];
        void init(){
            wordEnd = 0;
            fail = -1;
            memset(next, 0, sizeof(next));
        }    
}tree[MAXN];
int cnt;
char str[1000010];

void preProcess(){
        cnt = 0;
        tree[0].init();
}
void inline insert(char *str){
        int idx = 0;
        while( *str ){
            int i = *str - 'a';
            if( !tree[idx].next[i] ){
                    tree[++cnt].init();
                    tree[idx].next[i] = cnt;
            }
            idx = tree[idx].next[i];
            str++;
        }
        tree[idx].wordEnd++;
}
void BFS(){
        queue<int> que;
        int fail, fa, idx;
        que.push(0);        //根节点进队
         //front = rear = 0;
        //que[rear++] = 0;
        while( !que.empty() ){
            fa = que.front();
            que.pop();
            //fa = que[front++];
            for(int i = 0; i < K; ++i){
                    if( tree[fa].next[i] ){    
                        fail = tree[fa].fail;
                        idx = tree[fa].next[i];
                        que.push(idx);            //所有节点进队一次
                           //que[rear++] = idx;
                        while(fail != -1 && tree[fail].next[i] == 0){
                                fail = tree[fail].fail;
                        }    
                        if(fail == -1)
                                tree[idx].fail = 0;
                        else
                                tree[idx].fail = tree[fail].next[i];
                    }
            }
        }
}
void AC(char *str){
        int ans = 0, i, idx = 0, fail;
        while( *str ){
            i = *str - 'a';
            if( tree[idx].next[i] ) {    //相同 
                    idx = tree[idx].next[i];
            } else {            
                  fail = tree[idx].fail;    //指向失败指针
                    while(fail != -1 && tree[fail].next[i] == 0){
                        fail = tree[fail].fail;
                    }    
                    if(fail == -1){        //一直到根节点 都失配
                           idx = 0;    //
                    } else {        //tree[fail].next[i] ！= 0
                        idx = tree[fail].next[i];
                    }
            }
                //important
            int p = idx;
            while ( p != 0 && tree[p].wordEnd ){
                    if( tree[p].wordEnd ){
                        ans += tree[p].wordEnd;
                        tree[p].wordEnd = 0;        
                    }
                    p = tree[p].fail;        
            }
            str++;
        }
        printf("%d\n",ans);
}
int main(){
        int t, n;
        scanf("%d",&t);
        while( t-- ){
            preProcess();
            scanf("%d",&n);
            while( n-- ){
                    scanf("%s",str);
                    insert(str);
            }
            BFS();
            scanf("%s",str);
            AC(str);
        }
        return 0;
}