POJ1509 Glass Beads 后缀自动机

Posted 2021-02-05 menhera

题目分析：

模板练手。看最长能走多远。

代码:

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<string>
 6 using namespace std;
 7 
 8 const int maxn = 50500;
 9 
10 int son[maxn][30],fa[maxn],maxlen[maxn],root,num;
11 
12 string str;
13 
14 int addnew(int dt){maxlen[++num] = dt;return num;}
15 int ins(char x,int p){
16     int np = addnew(maxlen[p]+1);
17     while(p && !son[p][x-‘a‘]) son[p][x-‘a‘] = np,p = fa[p];
18     if(!p){fa[np] = root; return np;}
19     else{
20     int q = son[p][x-‘a‘];
21     if(maxlen[q]==maxlen[p]+1){fa[np]=q;return np;}
22     else{
23         int nq = addnew(maxlen[p]+1);
24         for(int i=0;i<26;i++) son[nq][i] = son[q][i];
25         fa[nq] = fa[q]; fa[q] = fa[np] = nq;
26         while(p && son[p][x-‘a‘] == q) son[p][x-‘a‘] = nq,p = fa[p];
27         return np;
28     }
29     }
30 }
31 
32 void dfs(int now,int cnt){
33     int flag = 0;
34     for(int i=0;i<26;i++){
35     if(!son[now][i]) continue;
36     dfs(son[now][i],cnt+1); flag = 1;
37     break;
38     }
39     if(!flag){cout<<str.length()-cnt+1<<endl;}
40 }
41 
42 void init(){
43     for(int i=1;i<=num;i++) memset(son[i],0,sizeof(son[i]));
44     for(int i=1;i<=num;i++) fa[i] = maxlen[i] = 0;
45     root = 0; num = 0;
46 }
47 
48 void work(){
49     int lst = addnew(0);root = lst;
50     for(int i=0;i<str.length();i++)
51     lst = ins(str[i],lst);
52     dfs(root,0);
53 }
54 
55 int main(){
56     ios::sync_with_stdio(false);
57     cin.tie(0);
58     int Tmp; cin >> Tmp;
59     while(Tmp--){
60     init();
61     cin >> str;
62     str+=str;
63     work();
64     }
65     return 0;
66 }