luogu 3804 【模板】后缀自动机

学习一波后缀自动机

求字符串$S$的所有出现次数不为1的子串的出现次数乘上该子串长度的最大值

 #include<iostream>
 #include<cstdio>
 #include<cstdlib>
 #include<cmath>
 #include<algorithm>
 #include<cstring>
 #include<vector>
 #include<queue>
 #include<map>
 #define rep(i,s,t) for(register int i=(s);i<=(t);++i)
 #define dwn(i,s,t) for(register int i=(s);i>=(t);--i)
 #define ren for(register int i=fst[x];i;i=nxt[i])
 #define Fill(x,t) memset(x,t,sizeof(x))
 #define ll long long
 #define inf 2139062143
 #define MAXN 2001000
 using namespace std;
 char s[MAXN];
 int n,rt,lst,tr[MAXN][],tot,sz[MAXN],mxlen[MAXN],rnk[MAXN],cnt[MAXN],fa[MAXN];
 ll ans;
 inline void extend(int c)
 {
     int p=lst,np=lst=++tot;mxlen[np]=mxlen[p]+,sz[np]=;
     for(;p&&!tr[p][c];p=fa[p]) tr[p][c]=np;
     if(!p) {fa[np]=rt;return ;}
     int q=tr[p][c];if(mxlen[q]==mxlen[p]+) {fa[np]=q;return ;}
     int nq=++tot;mxlen[nq]=mxlen[p]+;
     memcpy(tr[nq],tr[q],sizeof(tr[nq]));
     fa[nq]=fa[q],fa[np]=fa[q]=nq;
     for(;p&&tr[p][c]==q;p=fa[p]) tr[p][c]=nq;
 }
 void build()
 {
     rep(i,,tot) cnt[mxlen[i]]++;rep(i,,n) cnt[i]+=cnt[i-];
     rep(i,,tot) rnk[cnt[mxlen[i]]--]=i;int p;
     dwn(i,tot,)
     {
         p=rnk[i],sz[fa[p]]+=sz[p];
         if(sz[p]>) ans=max(ans,1LL*sz[p]*mxlen[p]);
     }
 }
 int main()
 {
     rt=lst=tot=;scanf("%s",s+);n=strlen(s+);
     rep(i,,n) extend(s[i]-'a');
     build();printf("%lld\n",ans);
 }