bzoj 2938 AC自动机 + dfs判环

#include<bits/stdc++.h>
#define LL long long
#define ll long long
#define fi first
#define se second
#define mk make_pair
#define PII pair<int, int>
#define y1 skldjfskldjg
#define y2 skldfjsklejg

using namespace std;

const int N =  + ;
const int M = 1e7 + ;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = ;

int n, m;
char s[N];

struct Ac {
    int ch[N][], val[N], dp[N], f[N], tot, sz;
    int vis[N];
    Ac(int sz) {this->sz = sz;}
    void init() {tot = ;};
    int newNode() {
        tot++; f[tot] = ; val[tot] = ;
        memset(ch[tot], , sizeof(ch[tot]));
        return tot;
    }
    inline int idx(char c) {return c - '';}
    void addStr(char *s) {
        int u = ;
        for(int i = ; s[i]; i++) {
            int c = idx(s[i]);
            if(!ch[u][c]) ch[u][c] = newNode();
            u = ch[u][c];
        }
        val[u] = ;
    }
    void build() {
        queue<int> que;
        for(int c = ; c < sz; c++) {
            int v = ch[][c];
            if(!v) ch[][c] = ;
            else f[v] = , que.push(v);
        }
        while(!que.empty()) {
            int u = que.front(); que.pop();
            val[u] |= val[f[u]];
            for(int c = ; c < sz; c++) {
                int v = ch[u][c];
                if(!v) ch[u][c] = ch[f[u]][c];
                else f[v] = ch[f[u]][c], que.push(v);
            }
        }
    }

    bool dfs(int u) {
        vis[u] = -;
        for(int c = ; c < sz; c++) {
            int v = ch[u][c];
            if(val[v] || vis[v] == ) continue;
            if(vis[v] == - || dfs(v)) return true;
        }
        vis[u] = ;
        return false;
    }

    void solve() {
        memset(vis, , sizeof(vis));
        queue<int> que;
        que.push();
        printf("%s\n", dfs() ? "TAK" : "NIE");
    }
} ac();
int main() {
    ac.init();
    scanf("%d", &n);
    for(int i = ; i < n; i++) {
        scanf("%s", s);
        ac.addStr(s);
    }
    ac.build();
    ac.solve();
    return ;
}

/*
2
abad
ba
-----
*/