后缀自动机

后缀自动机

const int CHAR = 26;
const int MAXN = 250010;

struct SAM_Node
{
SAM_Node *fa, *next[CHAR];
int len;
int id, pos;
SAM_Node(){}
SAM_Node(int _len)
{
fa = 0;
len = _len;
memset(next, 0, sizeof(next));
}
};

SAM_Node SAM_node[MAXN * 2], *SAM_root, *SAM_last;
int SAM_size;
SAM_Node *newSAM_Node(int len)
{
SAM_node[SAM_size] = SAM_Node(len);
SAM_node[SAM_size].id = SAM_size;
return &SAM_node[SAM_size++];
}
SAM_Node *newSAM_Node(SAM_Node *p)
{
SAM_node[SAM_size] = *p; SAM_node[SAM_size].id = SAM_size;
return &SAM_node[SAM_size++];
}
void SAM_init()
{
SAM_size = 0;
SAM_root = SAM_last = newSAM_Node(0);
SAM_node[0].pos = 0;
}
void SAM_add(int x, int len)
{
SAM_Node *p = SAM_last, *np = newSAM_Node(p->len+1);
np->pos = len;
SAM_last = np;
for (; p && !p->next[x]; p = p->fa)
{
p->next[x] = np;
}
if (!p)
{
np->fa = SAM_root;
return;
}
SAM_Node *q = p->next[x];
if (q->len == p->len + 1)
{
np->fa = q;
return ;
}
SAM_Node *nq = newSAM_Node(q);
nq->len = p->len + 1;
q->fa = nq;
np->fa = nq;
for(;p && p->next[x] == q; p = p->fa)
p->next[x] = nq;
}
void SAM_build(char *s)
{
SAM_init();
int len = (int)strlen(s);
for (int i = 0; i < len; i++)
{
SAM_add(s[i] - 'a', i + 1);
}
}

/*
//  加入串后进行拓扑排序
char str[MAXN];
int topocnt[MAXN];
SAM_Node *topsam[MAXN * 2];
int n = (int)strlen(str);
SAM_build(str);
memset(topocnt, 0, sizeof(topocnt));
for (int i = 0; i < SAM_size; i++)
{
topocnt[SAM_node[i].len]++;
}
for (int i = 1; i <= n; i++)
{
topocnt[i] += topocnt[i-1];
}
for (int i = 0; i < SAM_size; i++)
{
topsam[--topocnt[SAM_node[i].len]] = &SAM_node[i];
}
*/

//  多串的建立:
//  多串的建立,注意SAM_init()的调用
//void SAM_build(char *s)
//{
//    int len = (int)strlen(s);
//    SAM_last = SAM_root;
//    for (int i = 0; i < len; i++)
//    {
//        if (!SAM_last->next[s[i] - '0'] || !(SAM_last->next[s[i] - '0']->len == i+1))
//        {
//            SAM_add(s[i] - '0',i+1);
//        }
//        else
//        {
//            SAM_last = SAM_last->next[s[i] - '0'];
//        }
//    }
//}