病毒侵袭持续中 【HDU - 3065】【AC自动机】

题目链接

  就是求的是每个病毒出现的次数，可以重叠……嗯，最后别忘了释放内存，不然听说会MLE（但是我比较规矩……不会遇到这种现象的，MLE了一次，就记得要释放内存了）。

  是一道AC自动机的模板题。

#include <iostream>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
#include <limits>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#define lowbit(x) ( x&(-x) )
#define pi 3.141592653589793
#define e 2.718281828459045
#define INF 0x3f3f3f3f
#define HalF (l + r)>>1
#define lsn rt<<1
#define rsn rt<<1|1
#define Lson lsn, l, mid
#define Rson rsn, mid+1, r
#define QL Lson, ql, qr
#define QR Rson, ql, qr
#define myself rt, l, r
#define MP(a, b) make_pair(a, b)
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const int maxN = 2e6 + 7;
int N, ans[1005];
char virus[1005][55], sss[maxN];
struct node
{
    node *next[26];
    node *fail;
    int sum, id;
    node()
    {
        memset(next, 0, sizeof(next));
        fail = NULL;
        sum = id = 0;
    }
};
node *root;
void update(char *s, int id)
{
    node *temp = root;
    int len = (int)strlen(s);
    for(int i=0; i<len; i++)
    {
        int x = s[i] - 'A';
        if(temp->next[x] == NULL) temp->next[x] = new node();
        temp = temp->next[x];
    }
    temp->sum++;
    temp->id = id;
}
void build_fail()
{
    queue<node *> Q;
    Q.push(root);
    node *p, *temp;
    while(!Q.empty())
    {
        temp = Q.front();   Q.pop();
        for(int i=0; i<26; i++)
        {
            if(temp->next[i])
            {
                if(temp == root) temp->next[i]->fail = root;
                else
                {
                    p = temp->fail;
                    while(p)
                    {
                        if(p->next[i]) { temp->next[i]->fail = p->next[i]; break; }
                        p = p->fail;
                    }
                    if(p == NULL) temp->next[i]->fail = root;
                }
                Q.push(temp->next[i]);
            }
        }
    }
}
bool check(char s) { return s>='A' && s<='Z'; }
void AC_auto(char *s)
{
    node *p = root, *temp;
    int len = (int)strlen(s);
    for(int i=0; i<len; i++)
    {
        if(!check(s[i])) { p = root; continue; }
        int x = s[i] - 'A';
        while(p != root && !p->next[x]) p = p->fail;
        p = p->next[x];
        if(!p) p = root;
        temp = p;
        while(temp != root && temp->sum >= 0)
        {
            if(temp->sum) ans[temp->id]++;
            temp = temp->fail;
        }
    }
}
inline void init()
{
    root = (node *)malloc(sizeof(node));
    for(int i=0; i<26; i++) root->next[i] = NULL;
    root->fail = NULL;
    root->sum = 0;
    memset(ans, 0, sizeof(ans));
}
inline void FREE(node *temp)
{
    for(int i=0; i<26; i++) if(temp->next[i]) FREE(temp->next[i]);
    free(temp);
}
int main()
{
    while(scanf("%d", &N)!=EOF)
    {
        init();
        for(int i=1; i<=N; i++)
        {
            scanf("%s", virus[i]);
            update(virus[i], i);
        }
        build_fail();
        scanf("%s", sss);
        AC_auto(sss);
        for(int i=1; i<=N; i++) if(ans[i]) printf("%s: %d\n", virus[i], ans[i]);
        FREE(root);
    }
    return 0;
}
/*
2
AA
AAA
ooxxCC%dAAAoen....ENDooxxCC%dAAAoen....ENDooxxCC%dAAAoen....ENDooxxCC%dAAAoen....END
ans:
AA: 8
AAA: 4
*/

后面再附上静态的加上last优化的模板。

#include <iostream>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
#include <limits>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <bitset>
#include <unordered_map>
#include <unordered_set>
#define lowbit(x) ( x&(-x) )
#define pi 3.141592653589793
#define e 2.718281828459045
#define INF 0x3f3f3f3f
#define HalF (l + r)>>1
#define lsn rt<<1
#define rsn rt<<1|1
#define Lson lsn, l, mid
#define Rson rsn, mid+1, r
#define QL Lson, ql, qr
#define QR Rson, ql, qr
#define myself rt, l, r
using namespace std;
typedef unsigned long long ull;
typedef unsigned int uit;
typedef long long ll;
const int maxN = 1e3 + 7;
int N, tot;
char s[maxN][55], text[2000006];
struct node
{
    int nex[26], fail, last, id;
    node() { fail = last = id = 0; for(int i=0; i<26; i++) nex[i] = 0; }
}a[maxN * 50];
inline void Insert(int id)
{
    int u = 0, len = (int)strlen(s[id]);
    for(int i=0, Index; i<len; i++)
    {
        Index = s[id][i] - 'A';
        if(!a[u].nex[Index])
        {
            a[++tot] = node();
            a[u].nex[Index] = tot;
        }
        u = a[u].nex[Index];
    }
    a[u].id = id;
}
queue<int> Q;
inline void build_Fail()
{
    while(!Q.empty()) Q.pop();
    Q.push(0);
    int u, v, p;
    while(!Q.empty())
    {
        u = Q.front(); Q.pop();
        for(int i=0; i<26; i++)
        {
            v = a[u].nex[i];
            if(v)
            {
                if(!u) a[u].fail = 0;
                else
                {
                    p = a[u].fail;
                    while(p && !a[p].nex[i]) p = a[p].fail;
                    a[v].fail = a[p].nex[i];
                }
                if(a[a[v].fail].id) a[v].last = a[v].fail;
                else a[v].last = a[a[v].fail].last;
                Q.push(v);
            }
        }
    }
}
int ans[maxN];
inline void Ac_Auto()
{
    int len = (int)strlen(text), u = 0, p;
    for(int i=0, id; i<len; i++)
    {
        id = text[i] - 'A';
        if(id < 0 || id >= 26) { u = 0; continue; }
        while(u && !a[u].nex[id]) u = a[u].fail;
        u = a[u].nex[id];
        if(!u) continue;
        p = u;
        while(p)
        {
            if(a[p].id) ans[a[p].id]++;
            p = a[p].last;
        }
    }
}
inline void init()
{
    tot = 0;
    a[0] = node();
    for(int i=1; i<=N; i++) ans[i] = 0;
}
int main()
{
    while(scanf("%d", &N) != EOF)
    {
        init();
        for(int i=1; i<=N; i++)
        {
            scanf("%s", s[i]);
            Insert(i);
        }
        build_Fail();
        scanf("%s", text);
        Ac_Auto();
        for(int i=1; i<=N; i++)
        {
            if(!ans[i]) continue;
            printf("%s: %d\n", s[i], ans[i]);
        }
    }
    return 0;
}