SPOJ LCS2 后缀自动机

多串的LCS,注意要利用拓扑序更新suf的len。

我用min,max,三目会超时，所以都改成了if,else

#pragma warning(disable:4996)

#include<cstring>

#include<string>

#include<iostream>

#include<cmath>

#include<vector>

#include<algorithm>

#define maxn 100050

using namespace std;



struct State{

	State *suf, *go[26];

	int val, len[2];

	State() :suf(0), val(0){

		memset(go, 0, sizeof(go));

		memset(len, 0, sizeof(len));

	}

}*root, *last;



State statePool[maxn * 2], *cur;



void init()

{

	cur = statePool;

	root = last = cur++;

}



void extend(int w)

{

	State *p = last, *np = cur++;

	np->val = p->val + 1;

	np->len[1] = np->val;

	while (p&&!p->go[w]) p->go[w] = np, p = p->suf;

	if (!p) np->suf = root;

	else{

		State *q = p->go[w];

		if (p->val + 1 == q->val){

			np->suf = q;

		}

		else{

			State *nq = cur++;

			memcpy(nq->go, q->go, sizeof q->go);

			nq->val = p->val + 1;

			nq->len[1] = nq->val;

			nq->suf = q->suf;

			q->suf = nq;

			np->suf = nq;

			while (p&&p->go[w] == q){

				p->go[w] = nq, p = p->suf;

			}

		}

	}

	last = np;

}



char str[maxn];

int n;



int bcnt[maxn];

State *b[maxn * 2];



int main()

{

	n = 0;

	scanf("%s", str);

	init();

	int len = strlen(str);

	for (int i = 0; i < len; i++){

		extend(str[i] - 'a');

	}

	int tot = cur - root;

	memset(bcnt, 0, sizeof(bcnt));

	for (int i = 0; i < tot; i++) bcnt[statePool[i].val]++;

	for (int i = 1; i <= len; i++) bcnt[i] += bcnt[i - 1];

	for (int i = tot - 1; i >= 0; i--) b[--bcnt[statePool[i].val]] = &statePool[i];

	while (scanf("%s", str) != EOF){

		int lenb = strlen(str);

		int cnt = 0;

		State *p = root;

		for (int i = 0; i < lenb; i++){

			if (p->go[str[i] - 'a']){

				cnt++;

				p = p->go[str[i] - 'a'];

			}

			else{

				while (p&&!p->go[str[i] - 'a']) p = p->suf;

				if (!p) {

					p = root;

					cnt = 0;

				}

				else{

					cnt = p->val + 1;

					p = p->go[str[i] - 'a'];

				}

			}

			if (cnt > p->len[0]){

				p->len[0] = cnt;

			}

		}

		for (int i = tot - 1; i >= 0; i--){

			if (b[i]->len[0]<b[i]->len[1]) b[i]->len[1] = b[i]->len[0];

			if (b[i]->suf&&b[i]->suf->len[0]< b[i]->len[0]){

				b[i]->suf->len[0] = b[i]->len[0];

			}

			b[i]->len[0] = 0;

		}

	}

	int ans = 0;

	for (int i = 0; i < tot; i++){

		if (ans < b[i]->len[1]){

			ans = b[i]->len[1];

		}

	}

	printf("%d\n", ans);

	return 0;

}