HDU 3065 病毒侵袭持续中

最新推荐文章于 2020-07-27 19:43:52 发布

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本文介绍了一道AC自动机模板题的实现思路及代码细节，包括节点结构定义、插入操作、失败指针构造及匹配过程。

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AC自动机模板题。感觉数据略水。从2896改过来的

#include<cstdio>
#include<string>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<iostream>
using namespace std;
#define N 2000005
char a[1005][55];
char b[N];
int n, m;
int sum;
struct Trie {
    Trie *fail;
    Trie *son[26];
    int ex;
};
Trie t[N];
Trie *que[N];
int num[1005];
int ptr;
Trie *NewNode(){
    Trie *p = &t[ptr++];
    memset(p->son, NULL, sizeof(p->son));
    p->fail = NULL;
    p->ex = 0;
    return p;
}
void Insert(int id, Trie *root){
    Trie *tmp = root;
    for(int i = 0; a[id][i]; i++){
        if(tmp->son[a[id][i] - 'A'] == NULL)
            tmp->son[a[id][i] - 'A'] = NewNode();
        tmp = tmp->son[a[id][i] - 'A'];
    }
    tmp->ex = id;
}
void gfail(Trie *root){
    int head = 0, tail = 0;
    que[tail++] = root;
    Trie *tmp;
    while(head < tail){
        tmp = que[head++];
        for(int i = 0; i < 26; i++){
            if(tmp->son[i] != NULL){
                Trie *next = tmp->fail;
                while(next != NULL && next->son[i] == NULL){
                    next = next->fail;
                }
                if(next == NULL)
                    tmp->son[i]->fail = root;
                else
                    tmp->son[i]->fail = next->son[i];
                que[tail++] = tmp->son[i];
            }
        }
    }
}
void AC(Trie *root){
    Trie *tmp = root;
    for(int i = 0; b[i]; i++){
        if(b[i] < 'A' || b[i] > 'Z')tmp = root;
        else {
            while(tmp->son[b[i] - 'A'] == NULL && tmp != root){
                tmp = tmp->fail;
            }
            if(tmp->son[b[i] - 'A'] == NULL)
                tmp = root;
            else
                tmp = tmp->son[b[i] - 'A'];
        }
        Trie *p = tmp;
        while(p != root){
            num[p->ex]++;
            p = p->fail;
        }
    }
}
int main()
{
    while(scanf("%d", &n) != EOF){
        memset(num, 0, sizeof(num));
        sum = 0;
        ptr = 0;
        Trie *root = NewNode();
        for(int i = 1; i <= n; i++){
            scanf("%s", a[i]);
            Insert(i, root);
        }
        gfail(root);
        scanf("%s", b);
        AC(root);
        for(int i = 1; i <= n; i++){
            if(num[i])printf("%s: %d\n", a[i], num[i]);
        }
    }
    return 0;
}