acm-reference/suff_automata.cpp at master · zaic/acm-reference · GitHub

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// ************** Construction of suffix automata in O(n) **************
const int maxl = 1 << 17;
const int maxn = 1 << 18;
const int maxa = 53;
char s[maxl];

struct node {
	int next[maxa], suff, len, end;
} nodes[maxn];
int root, cnt;
inline int new_node(int len) {
	memset(nodes + cnt, -1, sizeof(node));
	nodes[cnt].len = len;
	nodes[cnt].end = 0;
	return cnt++;
}

void extend(char c, int &last) {
	int nlast = new_node(nodes[last].len + 1), p;
	for (p = last; p >= 0 && nodes[p].next[numc(c)] == -1; p = nodes[p].suff)
		nodes[p].next[numc(c)] = nlast;
	last = nlast;
	if (p < 0) {
		nodes[nlast].suff = root;
		return;
	}
	int q = nodes[p].next[numc(c)];
	if (nodes[q].len == nodes[p].len + 1) {
		nodes[nlast].suff = q;
		return;
	}
	int nq = new_node(nodes[p].len + 1);
	memcpy(nodes[nq].next, nodes[q].next, sizeof(nodes[q].next));
	nodes[nlast].suff = nq;
	nodes[nq].suff = nodes[q].suff;
	nodes[q].suff = nq;
	for ( ; p >= 0 && nodes[p].next[numc(c)] == q; p = nodes[p].suff)
		nodes[p].next[numc(c)] = nq;
}

void create_automata() {
	int l = strlen(s), i, last;
	cnt = 0;
	last = root = new_node(0);
	for (i = 0; i < l; ++i) extend(s[i], last);
	for (i = last; i >= 0; i = nodes[i].suff) nodes[i].end = 1;
}