[Poj1509] glass beads [suffix automatic mechanism]

Question

Returns the minimum representation of a string.

Analysis

Of course, this question can be done in the smallest notation! But I want to learn the suffix!

We multiply the length of this string by two, then create Sam, and then run the smallest letter on Sam every time to find the length of N and then stop. If u is stopped, ANS = sT [u]. Len-n + 1

　　

 1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 #include <iostream> 5 #include <map> 6  7 using namespace std; 8 const int maxn=20000+100; 9 char s[maxn];10 int n,T;11 struct state{12     map<char,int>next;13     int len,link;14 }st[4*maxn];15 int last,cnt,cur;16 void init(){17     last=cur=0;18     cnt=1;19     st[0].len=0;20     st[0].link=-1;21     st[0].next.clear();22 }23 void build(char c){24     cur=cnt++;25     st[cur].next.clear();26     st[cur].len=st[last].len+1;27     int p;28     for(p=last;p!=-1&&!st[p].next.count(c);p=st[p].link)29         st[p].next[c]=cur;30     if(p==-1)31         st[cur].link=0;32     else{33         int q=st[p].next[c];34         if(st[p].len+1==st[q].len)35             st[cur].link=q;36         else{37             int clone=cnt++;38             st[clone].next=st[q].next;39             st[clone].link=st[q].link;40             st[clone].len=st[p].len+1;41             for(;p!=-1&&st  [p].next[c]==q;p=st[p].link)42                 st[p].next[c]=clone;43             st[q].link=clone;st[cur].link=clone;44         }45     }46     last=cur;47 }48 int main(){49     scanf("%d",&T);50     for(int t=1;t<=T;t++){51         scanf("%s",s);52         n=strlen(s);53         for(int i=0;i<n;i++)54             s[i+n]=s[i];55         init();56         for(int i=0;i<n;i++)57             build(s[i]);58         for(int i=n;i<2*n;i++)59             build(s[i]);60         int u=0;61         for(int i=0;i<n;i++){62             for(int j=‘a‘;j<=‘z‘;j++){63                 if(st[u].next.count(j)){64                     u=st[u].next[j];65                     break;66                 }67             }68         }69         int ans=st[u].len-n+1;70         printf("%d\n",ans);71     }72 return 0;73 }

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[Poj1509] glass beads [suffix automatic mechanism]