UVALive 4670 Dominating Patterns --AC自动机第一题

题意：多个模板串，一个文本串，求出那些模板串在文本串中出现次数最多。

解法：AC自动机入门模板题。

代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <map>
#define Mod 1000000007
using namespace std;
#define N 1000007

const int MAXNODE = 20005;
const int SIZE = 26;
int cnt[MAXNODE];
struct Trie {
    int ch[MAXNODE][SIZE],val[MAXNODE],sz,fail[MAXNODE],last[MAXNODE];
    Trie() { sz = 1; memset(ch[0],0,sizeof(ch[0])); }
    int idx(char c) { return c-'a'; };
    void init() { sz = 1; memset(ch[0],0,sizeof(ch[0])); memset(cnt,0,sizeof(cnt)); }
    void print(int j) {
        if(j) {
            cnt[val[j]]++;
            print(last[j]);
        }
        return;
    }
    void Insert(char *s,int v) {
        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] = v;
    }
    void getFail() {
        queue<int> q;
        fail[0] = 0;
        for(int c=0;c<SIZE;c++) {
            int u = ch[0][c];
            if(u) { fail[u] = 0; q.push(u); last[u] = 0; }
        }
        while(!q.empty()) {
            int r = q.front(); q.pop();
            for(int c=0;c<SIZE;c++) {
                int u = ch[r][c];
                if(!u) continue;
                q.push(u);
                int v = fail[r];
                while(v && !ch[v][c]) v = fail[v];
                fail[u] = ch[v][c];
                last[u] = val[fail[u]] ? fail[u] : last[fail[u]];
            }
        }
    }
    void query(char *T) {
        int n = strlen(T), j = 0;
        for(int i=0;i<n;i++) {
            int c = idx(T[i]);
            while(j && !ch[j][c]) j = fail[j];
            j = ch[j][c];
            if(val[j]) print(j);
            else if(last[j]) print(last[j]);
        }
    }
};
char T[N],ss[160][77];
map<string,int> mp;
Trie ac;

int main()
{
    int n,i;
    while(scanf("%d",&n)!=EOF && n)
    {
        mp.clear();
        ac.init();
        for(i=1;i<=n;i++) {
            scanf("%s",ss[i]);
            ac.Insert(ss[i],i);
            mp[string(ss[i])] = i;
        }
        ac.getFail();
        scanf("%s",T);
        ac.query(T);
        int Maxi = -1;
        for(i=1;i<=n;i++)
            Maxi = max(Maxi,cnt[i]);
        cout<<Maxi<<endl;
        for(i=1;i<=n;i++) {
            if(cnt[mp[string(ss[i])]] == Maxi)
                printf("%s
",ss[i]);
        }
    }
    return 0;
}