HDU 2222 Keywords Search（AC自动机模板题）

题意：给出一个字符串和若干个模板，求出在文本串中出现的模板个数。

思路：因为有可能有重复的模板，trie树权值记录每个模板出现的次数即可。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#include<vector>
#include<map>
#include<queue>
#include<stack>
#include<string>
#include<map>
#include<set>
#include<ctime>
#define eps 1e-6
#define LL long long
#define pii (pair<int, int>)
//#pragma comment(linker, "/STACK:1024000000,1024000000")
using namespace std;

const int maxn = 1000000 + 100;
const int SIGMA_SIZE = 26;
const int maxnode = 1000000+100;
int n, ans;
bool vis[maxn];
map<string, int> ms;
int ch[maxnode][SIGMA_SIZE+5];
int val[maxnode];
int idx(char c) {return c - 'a';}
struct Trie {
    int sz;
    Trie() { sz = 1; memset(ch[0], 0, sizeof(ch[0])); memset(vis, 0, sizeof(vis)); }
    void insert(char *s) {
        int u = 0, n = strlen(s);
        for(int i = 0; i < n; i++) {
            int c = idx(s[i]);
            if(!ch[u][c]) {
                memset(ch[sz], 0, sizeof(ch[sz]));
             	val[sz] = 0;
                ch[u][c] = sz++;
            }
            u = ch[u][c];
        }
        val[u]++;
    }
};  

//ac自动机
int last[maxn], f[maxn];
void print(int j) {
	if(j && !vis[j]) {
		ans += val[j]; vis[j] = 1;
		print(last[j]);
	}
} 

int getFail() {
	queue<int> q;
	f[0] = 0;
	for(int c = 0; c < SIGMA_SIZE; c++) {
		int u = ch[0][c];
		if(u) {
			f[u] = 0; q.push(u); last[u] = 0;
		}
	}
	while(!q.empty()) {
		int r = q.front(); q.pop();
		for(int c = 0; c < SIGMA_SIZE; c++) {
			int u = ch[r][c];
			if(!u) {
				ch[r][c] = ch[f[r]][c];
				continue;
			}
			q.push(u);
			int v = f[r];
			while(v && !ch[v][c]) v = f[v];
			f[u] = ch[v][c];
			last[u] = val[f[u]] ? f[u] : last[f[u]];
		}
	}
}

void find_T(char* T) {
	int n = strlen(T);
	int j = 0;
	for(int i = 0; i < n; i++) {
		int c = idx(T[i]);
		j = ch[j][c];
		if(val[j]) print(j);
		else if(last[j]) print(last[j]);
	}
} 

char tmp[105];
char text[1000000+1000];
int main() {
    //freopen("input.txt", "r", stdin);
	int T; cin >> T;
	while(T--) {
		scanf("%d", &n);
		Trie trie;
		ans = 0;
		for(int i = 0; i < n; i++) {
			scanf("%s", tmp);
			trie.insert(tmp);
		}
		getFail();
		scanf("%s", text);
		find_T(text);
		cout << ans << endl;
	}
    return 0;
}

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