kuangbin专题十七：AC自动机

HDU2222 Keywords Search

思路：AC自动机模板。

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
using namespace std;
const int maxn = 1e6+5;
int tr[maxn][26], tot;
int e[maxn], fail[maxn];
char s[maxn];

void insert(char *s){
    int u = 0;
    for(int i = 1; s[i]; i++){
        if(!tr[u][s[i]-'a']) tr[u][s[i]-'a'] = ++tot;
        u = tr[u][s[i]-'a'];
    }
    e[u]++;
}

queue<int> q;
void build(){
    for(int i = 0; i < 26; i++)
        if(tr[0][i]) q.push(tr[0][i]);
    while(q.size()){
        int u = q.front(); q.pop();
        for(int i = 0; i < 26; i++)
            if(tr[u][i])
                fail[tr[u][i]] = tr[fail[u]][i], q.push(tr[u][i]);
            else
                tr[u][i] = tr[fail[u]][i];
    }
}

int query(char *t){
    int u = 0, res = 0;
    for(int i = 1; t[i]; i++){
        u = tr[u][t[i]-'a'];
        for(int j = u; j && e[j]!=-1; j = fail[j])
            res += e[j], e[j] = -1;
    }
    return res;
}

void init(){
    tot = 0;
    memset(tr, 0, sizeof(tr));
    memset(fail, 0, sizeof(fail));
    memset(e, 0, sizeof(e));
}

int main(){
    int T;
    scanf("%d", &T);
    while(T--){
        int n;
        init();
        scanf("%d", &n);
        for(int i = 0; i < n; i++) scanf("%s", s+1), insert(s);
        scanf("%s", s+1);
        build();
        printf("%d\n", query(s));
    }
    return 0;
}

 

HDU2896 病毒侵袭

思路：注意字符串范围是0-128。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
using namespace std;
const int maxn = 500 * 200 + 5;
int tr[maxn][130], e[maxn], fail[maxn];
int tot;
bool vis[505];
char s[10005];

void insert(int idx, char *s){
    int u = 0;
    for(int i = 1; s[i]; i++){
        if(!tr[u][s[i]]) tr[u][s[i]] = ++tot;
        u = tr[u][s[i]];
    }
    e[u] = idx;
}

queue<int> q;
void build(){
    int u = 0;
    for(int i = 0; i < 128; i++)
        if(tr[u][i]) q.push(tr[u][i]);
    while(q.size()){
        u = q.front(); q.pop();
        for(int i = 0; i < 128; i++){
            if(tr[u][i])
                fail[tr[u][i]] = tr[fail[u]][i], q.push(tr[u][i]);
            else
                tr[u][i] = tr[fail[u]][i];
        }
    }
}

void query(char *t){
    memset(vis, 0, sizeof(vis));
    int u = 0;
    for(int i = 1; t[i]; i++){
        u = tr[u][t[i]];
        for(int j = u; j && !vis[e[j]]; j = fail[j]){
            if(e[j]) vis[e[j]] = 1;
        }
    }
}

void init(){
    memset(tr, 0, sizeof(tr));
    memset(e, 0, sizeof(e));
    memset(fail, 0, sizeof(fail));
    tot = 0;
}

int main(){
    int n, m, res = 0;
    scanf("%d", &n);
    for(int i = 0; i < n; i++) scanf("%s", s + 1), insert(i+1, s);
    build();
    scanf("%d", &m);
    for(int i = 1; i <= m; i++){
        scanf("%s", s+1);
        query(s);

        int tot = 0;
        for(int i = 1; i <= 500; i++) if(vis[i]) tot++;

        if(tot){
            printf("web %d:", i);
            for(int j = 1; j <= 500; j++)
                if(vis[j]) printf(" %d", j);
            printf("\n");
            res++;
        }
    }
    printf("total: %d\n", res);
    return 0;
}

 

HDU3065 病毒侵袭持续中

思路：同上。