LCS2 Longest Common Substring II (求若干個串的最長公共子串模板題)
阿新 • • 發佈:2019-02-04
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 is a bit harder, for some given strings, find the length of the longest common substring of them.
Here common substring means a substring of two or more strings.
Input
The input contains at most 10 lines, each line consists of no more than 100000 lowercase letters, representing a string.
Output
The length of the longest common substring. If such string doesn't exist, print "0" instead.
Example
Input:alsdfkjfjkdsal fdjskalajfkdsla aaaajfaaaa Output: 2
#include<cstdio> #include<cstring> using namespace std; const int MAXN = 3*1e5+10; //串的長度最大為1e5但空間儘量大點。 char s[MAXN]; int sz,last,root,l[MAXN],ch[MAXN][26],fa[MAXN],mn[MAXN],mx[MAXN]; int b[MAXN],cnt[MAXN]; void add(int x) { int c = s[x]-'a';//如果串由大寫字母組成改這裡 int p=last,np=++sz; last=np; l[np]=mn[np]=x+1; for(;p&&!ch[p][c];p=fa[p]) ch[p][c]=np; if(!p) fa[np]=root; else { int q=ch[p][c]; if(l[p]+1==l[q]) fa[np]=q; else { int nq=++sz; l[nq]=mn[nq]=l[p]+1; memcpy(ch[nq],ch[q],sizeof(ch[q])); fa[nq]=fa[q]; fa[np]=fa[q]=nq; for(;ch[p][c]==q;p=fa[p]) ch[p][c]=nq; } } } int main() { root = last = ++sz; scanf("%s",s);//先讀第一串 int len=strlen(s); for(int i=0;i<len;i++) add(i); for(int i=1;i<=sz;i++) cnt[l[i]]++; for(int i=1;i<=len;i++) cnt[i]+=cnt[i-1]; for(int i=1;i<=sz;i++) b[cnt[l[i]]--]=i; while(scanf("%s",s) == 1) { int p=root; len=0; for(int i=0 ; s[i] ; ++i) { int c = s[i]-'a';//如果串由大寫字母組成改這裡 if(ch[p][c]) { len++; p=ch[p][c]; } else { while(p&&!ch[p][c]) p=fa[p]; if(!p) { len=0; p=root; } else { len=l[p]+1; p=ch[p][c]; } } if(len>mx[p]) mx[p]=len; } for(int i=sz ; i ; i--) { p=b[i]; if(mx[p]<mn[p]) mn[p]=mx[p]; if(fa[p] && mx[fa[p]]<mx[p]) mx[fa[p]]=mx[p]; mx[p]=0; } } int ans=0; for(int i=1 ; i<=sz ; ++i) if(mn[i]>ans) ans=mn[i]; printf("%d",ans); return 0; }