【SPOJ1811】Longest Common Substring（后缀自动机）

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[SPOJ1811]Longest Common Substring 后缀自动机最长公共子串

题目链接:http://www.spoj.com/problems/LCS/ 题意如题目,求两个串的最大公共子串LCS. 首先对其中一个字符串A建立SAM,然后用另一个字符串B在上面跑. 用一个变量Lcs来记录当前答案,如果能转移到下一个状态则Lcs++. 若不能转移说明需要重新选择状态,则不断地跳到当前状态的fa状态,如果发现能够转移就停下来,Lcs变为当前状态的len+1并转移到下一个可行状态. 这里很像AC自动机的fail指针的跳跃.因为fa状态是当前状态的后缀,已经被匹配过,而fa状态有…

SPOJ1811 LCS - Longest Common Substring(后缀自动机)

A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occurrences at least once in a string. Now your task i…

SPOJ 1811 Longest Common Substring 后缀自动机

模板来源:http://www.neroysq.com/?p=76 思路:http://blog.sina.com.cn/s/blog_7812e98601012dfv.html 题意就是求两个字符串的最长公共子串,串长最大250000. 以串A构建一个后缀自动机,用串B来匹配.枚举串B的每一位B[i]即考虑串B中所有以B[i]为结尾的子串,维护的值为以B[i]为末尾能匹配的最大长度tmpL. 假设走到B[i]时已经匹配好的串为str,如果当前节点有B[i]这个儿子,直接向下走,++tmpL.…

SPOJ 1811 Longest Common Substring (后缀自动机第一题，求两个串的最长公共子串)

题目大意: 给出两个长度小于等于25W的字符串,求它们的最长公共子串. 题目链接:http://www.spoj.com/problems/LCS/ 算法讨论: 二分+哈希, 后缀数组, 后缀自动机. 随意做.这里面只写一下我对后缀自动机做法的理解. 首先,我们假设两个串分别为A串和B串,我们先对建立出A串的后缀自动机,然后对于B串的每一位,我们进行如下的操作:首先从第1位开始,Parent树上的位置在root,那么对于每一次操作,如果当前结点的字符可以匹配当前B串中所考虑到的字符,那么自然就l…

spoj 1811 LCS - Longest Common Substring (后缀自己主动机)

spoj 1811 LCS - Longest Common Substring 题意: 给出两个串S, T, 求最长公共子串. 限制: |S|, |T| <= 1e5 思路: dp O(n^2) 铁定超时后缀数组 O(nlog(n)) 在spoj上没试过,感觉也会被卡掉后缀自己主动机 O(n) 我们考虑用SAM读入字符串B; 令当前状态为s,同一时候最大匹配长度为len; 我们读入字符x.假设s有标号为x的边,那么s=trans(s,x),len = len+1; 否则我们找到s的第一个祖…

spoj1811 Longest Common Substring

#include <iostream> #include <cstdio> #include <cstring> #include <cmath> #include <algorithm> #define maxn 500005 #define maxl 250005 using namespace std; ],fa[maxn],dist[maxn]; char s1[maxl],s2[maxl]; struct Tsegment{ ;} in…

hdu 1403 Longest Common Substring 后缀数组模板题

题目链接题意问两个字符串的最长公共子串. 思路加一个特殊字符然后拼接起来,求得后缀数组与\(height\)数组.扫描一遍即得答案,注意判断起始点是否分别在两个串内. Code #include <bits/stdc++.h> #define maxn 200010 using namespace std; typedef long long LL; int a[maxn], wa[maxn], wb[maxn], wv[maxn], wt[maxn], h[maxn], rk[maxn…

LCS - Longest Common Substring(spoj1811) (sam(后缀自动机)+LCS)

A string is finite sequence of characters over a non-empty finite set \(\sum\). In this problem, \(\sum\) is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occurrences at least once in a string. N…

【SPOJ】Longest Common Substring II （后缀自动机）

[SPOJ]Longest Common Substring II (后缀自动机) 题面 Vjudge 题意:求若干个串的最长公共子串题解对于某一个串构建\(SAM\) 每个串依次进行匹配同时记录\(f[i]\)表示走到了\(i\)节点能够匹配上的最长公共子串的长度当然,每个串的\(f[i]\)可以更新\(f[i.parent]\) 所以需要拓扑排序对于每个串求出每个节点的最长匹配然后对他们取\(min\),表示某个节点大家都能匹配的最长长度最后对于所有点的值都取个\(max\)…

【SPOJ】Longest Common Substring（后缀自动机）

[SPOJ]Longest Common Substring(后缀自动机) 题面 Vjudge 题意:求两个串的最长公共子串题解 \(SA\)的做法很简单不再赘述对于一个串构建\(SAM\) 另外一个串在\(SAM\)上不断匹配最后计算答案就好了匹配方法: 如果\(trans(s,c)\)存在直接沿着\(trans\)走就行,同时\(cnt++\) 否则沿着\(parent\)往上跳如果存在\(trans(now,c),cnt=now.longest+1\) 否则,如果不存在可行的…

LCS2 - Longest Common Substring II(spoj1812)(sam(后缀自动机)+多串LCS)

A string is finite sequence of characters over a non-empty finite set \(\sum\). In this problem, \(\sum\) is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occurrences at least once in a string. N…

SPOJ 1811. Longest Common Substring （LCS，两个字符串的最长公共子串，后缀自动机SAM）

1811. Longest Common Substring Problem code: LCS A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occur…

HDU 1403 Longest Common Substring（后缀自动机——附讲解 or 后缀数组）

Description Given two strings, you have to tell the length of the Longest Common Substring of them. For example:str1 = bananastr2 = cianaic So the Longest Common Substring is "ana", and the length is 3. Input The input contains several test case…

SPOJ 1812 Longest Common Substring II（后缀自动机）（LCS2）

A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occurrences at least once in a string. Now your task i…

spoj - Longest Common Substring（后缀自动机模板题）

Longest Common Substring 题意求两个串的最长公共子串. 分析第一个串建后缀自动机,第二个串在自动机上跑,对于自动机上的结点(状态)而言,它所代表的最大长度为根结点到当前结点的长度,而它的前继结点的串一定是这个结点串的后缀串(或空串). 匹配过程中一旦失配,自动机上的结点找它的前继结点,继续向后匹配即可. code #include<bits/stdc++.h> using namespace std; const int MAXN = 250005; char s[…

SPOJ LCS2 - Longest Common Substring II 后缀自动机多个串的LCS

LCS2 - Longest Common Substring II no tags A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occurrence…

Longest Common Substring II SPOJ - LCS2 （后缀自动机）

Longest Common Substring II \[ Time Limit: 236ms\quad Memory Limit: 1572864 kB \] 题意给出\(n\)个子串,要求这\(n\)个子串的最长连续公共子串长度. 思路前置技能:当 \(n=2\) 时的做法,可以先做做这题:SPOJ-LCS,我的博客:SPOJ-LCS题解这里为了方便,我们定义 \(LCS\) 为题中所求的最长连续公共子串. 当 \(n>2\) 时,我们可以对第一个串构建后缀自动机,然后用上一题一样的…

Longest Common Substring SPOJ - LCS （后缀自动机）

Longest Common Substring \[ Time Limit: 294ms \quad Memory Limit: 1572864 kB \] 题意给出两个串,求两个串的最长公共连续子序列的长度,两个串的长度小于等于250000. 思路先对第一个串构建后缀自动机,根据后缀自动机的性质,从 \(root\) 的所有路径都是原串中的子串,又因为构建的时候,我们用 \(node[i].len\) 表示与节点 \(i\) 的 \(endpos\) 相同的所有子串集合的最长长度,那么我…

SPOJ LCS Longest Common Substring 和 LG3804 【模板】后缀自动机

Longest Common Substring 给两个串A和B,求这两个串的最长公共子串. no more than 250000 分析参照OI wiki. 给定两个字符串 S 和 T ,求出最长公共子串,公共子串定义为在 S 和 T 中都作为子串出现过的字符串 X . 我们为字符串 S 构造后缀自动机. 我们现在处理字符串 T ,对于每一个前缀都在 S 中寻找这个前缀的最长后缀.换句话说,对于每个字符串 T 中的位置,我们想要找到这个位置结束的 S 和 T 的最长公共子串的长度. 为…

【SPOJ】1812. Longest Common Substring II（后缀自动机）

http://www.spoj.com/problems/LCS2/ 发现了我原来对sam的理解的一个坑233 本题容易看出就是将所有匹配长度记录在状态上然后取min后再对所有状态取max. 但是不要忘记了一点:更新parent树的祖先. 为什么呢?首先如果子树被匹配过了,那么长度一定大于任意祖先匹配的长度(甚至有些祖先匹配长度为0!为什么呢,因为我们在匹配的过程中,只是找到一个子串,可能还遗漏了祖先没有匹配到,这样导致了祖先的记录值为0,那么在对对应状态取min的时候会取到0,这样就wa了.而…

后缀自动机(SAM)：SPOJ Longest Common Substring II

Longest Common Substring II Time Limit: 2000ms Memory Limit: 262144KB A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecutive sequenc…

后缀自动机(SAM) ：SPOJ LCS - Longest Common Substring

LCS - Longest Common Substring no tags A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occurrences at…

spoj1811 LCS - Longest Common Substring

地址:http://www.spoj.com/problems/LCS/ 题面: LCS - Longest Common Substring no tags A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecut…

hdu 1403 Longest Common Substring(最长公共子字符串)（后缀数组）

http://acm.hdu.edu.cn/showproblem.php?pid=1403 Longest Common Substring Time Limit: 8000/4000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 3068 Accepted Submission(s): 1087 Problem Description Given two string…

后缀数组：HDU1043 Longest Common Substring

Longest Common Substring Time Limit: 8000/4000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 5375 Accepted Submission(s): 1910 Problem Description Given two strings, you have to tell the length of the Longest Co…

spoj 1812 LCS2 - Longest Common Substring II (后缀自己主动机)

spoj 1812 LCS2 - Longest Common Substring II 题意: 给出最多n个字符串A[1], ..., A[n], 求这n个字符串的最长公共子串. 限制: 1 <= n <= 10 |A[i]| <= 1e5 思路: 和spoj 1811 LCS几乎相同的做法把当中一个A建后缀自己主动机考虑一个状态s, 假设A之外的其它串对它的匹配长度各自是a[1], a[2], ..., a[n - 1], 那么min(a[1], a[2], ..., a[n -…

SPOJ LCS2 - Longest Common Substring II

LCS2 - Longest Common Substring II A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occurrences at leas…

【SP1811】LCS - Longest Common Substring

[SP1811]LCS - Longest Common Substring 题面洛谷题解建好后缀自动机后从初始状态沿着现在的边匹配, 如果失配则跳它的后缀链接,因为你跳后缀链接到达的\(Endpos\)集合中的串肯定是当前\(Endpos\)中的后缀,所以这么做是对的. 你感性理解一下,这样显然是最大的是吧... 具体实现看代码: 代码 #include <iostream> #include <cstdio> #include <cstdlib> #inclu…

SPOJLCS Longest Common Substring

题意 A string is finite sequence of characters over a non-empty finite set Σ. In this problem, Σ is the set of lowercase letters. Substring, also called factor, is a consecutive sequence of characters occurrences at least once in a string. Now your tas…

spoj Longest Common Substring

Longest Common Substring SPOJ - LCS 题意:求两个串的最长公共子串 /* 对一个串建立后缀自动机,用另一个串上去匹配 */ #include<iostream> #include<cstdio> #include<cstring> #define maxn 250002 using namespace std; char s1[maxn],s2[maxn]; ][],fa[maxn<<],tot=,len[maxn<&…