洛谷 3804 【模板】字尾自動機
阿新 • • 發佈:2018-12-12
題目:https://www.luogu.org/problemnew/show/P3804
學習材料:https://blog.csdn.net/qq_35649707/article/details/66473069
https://wenku.baidu.com/view/90f22eec551810a6f4248606.html
#include<cstdio> #include<cstring> #include<algorithm> #define ll long long using namespace std; const int N=1e6+5,M=N<<1,K=30; int cnt=1,go[M][K],fa[M],siz[M],l[M],lst=1;//=1 int tx[N],a[M];char ch[N]; ll Mx(ll a,ll b){return a>b?a:b;} void add(int w) { int p=lst,np=++cnt;lst=np;l[np]=l[p]+1; for(;p&&!go[p][w];p=fa[p])go[p][w]=np; if(!p)fa[np]=1;// 1 not 0 else { int q=go[p][w]; if(l[q]==l[p]+1)fa[np]=q; else { int nq=++cnt; l[nq]=l[p]+1; fa[nq]=fa[q]; fa[q]=nq; fa[np]=nq; memcpy(go[nq],go[q],sizeof go[q]); for(;go[p][w]==q;p=fa[p])go[p][w]=nq; } } siz[np]=1; } int main() { scanf("%s",ch);int n=strlen(ch); for(int i=0;i<n;i++)add(ch[i]-'a'+1); for(int i=1;i<=cnt;i++)tx[l[i]]++; for(int i=1;i<=n;i++)tx[i]+=tx[i-1]; for(int i=1;i<=cnt;i++)a[tx[l[i]]--]=i; ll ans=0; for(int i=cnt;i;i--) { int d=a[i]; siz[fa[d]]+=siz[d]; if(siz[d]>1)ans=Mx(ans,(ll)siz[d]*l[d]); } printf("%lld\n",ans); return 0; }