ZOJ 3430 Detect the Virus （AC自动机）

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题目链接：Detect the Virus

题意：n个模式串，一个文本串，问文本串包含几个模式串。

解析：解码 + AC自动机。

       解码过程：先将字符串转换成ASCII 然后根据相应的ASCII 转换成二进制，每一个是6位，不够加0，然后取8位为一个字符，求得的字符串为要的字符串。

AC代码：

#include <bits/stdc++.h>
using namespace std;

struct Trie{
    int next[520*64][256], fail[520*64], end[520*64];
    int root, L;

    int newnode(){
        for(int i = 0; i < 256; i++) next[L][i] = -1;
        end[L++] = -1;
        return L-1;
    }

    void init(){
        L = 0;
        root = newnode();
    }

    void insert(unsigned char buf[], int len, int id){
        int now = root;
        for(int i = 0; i < len; i++){
            if(next[now][ buf[i] ] == -1) next[now][ buf[i] ] = newnode();
            now = next[now][ buf[i] ];
        }
        end[now] = id;
    }

    void build(){
        queue<int> Q;
        fail[root] = root;
        for(int i = 0; i < 256; i++){
            if(next[root][i] == -1) next[root][i] = root;
            else{
                fail[ next[root][i] ] = root;
                Q.push(next[root][i]);
            }
        }
        while(!Q.empty()){
            int now = Q.front();
            Q.pop();
            for(int i = 0; i < 256; i++){
                if(next[now][i] == -1) next[now][i] = next[ fail[now] ][i];
                else{
                    fail[ next[now][i] ] = next[ fail[now] ][i];
                    Q.push(next[now][i]);
                }
            }
        }
    }

    bool used[520];
    int query(unsigned char buf[], int len, int n){
        memset(used, false, sizeof(used));
        int now = root;
        for(int i = 0; i < len; i++){
            now = next[now][ buf[i] ];
            int temp = now;
            while(temp != root){
                if(end[temp] != -1) used[ end[temp] ] = true;
                temp = fail[temp];
            }
        }
        int res = 0;
        for(int i = 0; i < n; i++)
            if(used[i]) res ++;
        return res;
    }
};

unsigned char buf[2050];
int tot;
char str[4000];
unsigned char s[4000];

unsigned char Get(char ch){
    if(ch >= 'A' && ch <= 'Z') return ch - 'A';
    if(ch >= 'a' && ch <= 'z') return ch - 'a' + 26;
    if(ch >= '0' && ch <= '9') return ch - '0' + 52;
    if(ch == '+') return 62;
    else return 63;
}

void change(unsigned char str[], int len){
    int t = 0;
    for(int i = 0; i < len; i+=4){
        buf[t++] = ((str[i]<<2) | (str[i+1]>>4));
        if(i+2 < len)
            buf[t++] = ((str[i+1]<<4) | (str[i+2]>>2));
        if(i+3 < len)
            buf[t++] = ((str[i+2]<<6) | (str[i+3]));
    }
    tot = t;
}

Trie ac;


int main(){
    #ifdef sxk
        freopen("in.txt", "r", stdin);
    #endif //sxk

    int n, m;
    while(scanf("%d", &n) == 1){
        ac.init();
        for(int i = 0; i < n; i++){
            scanf("%s", str);
            int len = strlen(str);
            while(str[len-1] == '=') len --;
            for(int j = 0; j < len; j++) s[j] = Get(str[j]);
            change(s, len);
            ac.insert(buf, tot, i);
        }
        ac.build();
        scanf("%d", &m);
        while(m --){
            scanf("%s", str);
            int len = strlen(str);
            while(str[len-1] == '=') len --;
            for(int j = 0; j < len; j++) s[j] = Get(str[j]);
            change(s, len);
            printf("%d\n", ac.query(buf, tot, n));
        }
        puts("");
    }
    return 0;
}

ZOJ 3430 Detect the Virus （AC自动机）

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原文地址：http://blog.csdn.net/u013446688/article/details/47360033