cf 700e(sam好题，线段树维护right)

代码参考：http://blog.csdn.net/qq_33229466/article/details/79140428

#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
const int maxn=;
int n,mx[maxn],ch[maxn][],fa[maxn],last=,id[maxn],tot=;
int dp[maxn],pos[maxn],cnt,b[maxn],c[maxn],root[maxn],ans;
char s[maxn];
struct node{
    int l,r;
}tr[maxn*];
void add(int i,int x){
    int p,q,np,nq;
    p=last;last=np=++tot;mx[np]=mx[p]+;id[np]=i;
    for(;!ch[p][x]&&p;p=fa[p])ch[p][x]=np;
    if(!p)fa[np]=;
    else{
        q=ch[p][x];
        if(mx[q]==mx[p]+)fa[np]=q;
        else{
            nq=++tot;mx[nq]=mx[p]+;id[nq]=i;
            memcpy(ch[nq],ch[q],sizeof(ch[q]));
            fa[nq]=fa[q];
            fa[q]=fa[np]=nq;
            for(;ch[p][x]==q;p=fa[p])ch[p][x]=nq;
        }
    }
}
void ins(int &d,int l,int r,int x){
    if(!d)d=++cnt;
    if(l==r)return;
    int mid=l+r>>;
    if(x<=mid)ins(tr[d].l,l,mid,x);
    else ins(tr[d].r,mid+,r,x);
}
int merge(int x,int y){
    if(!x||!y)return x+y;
    int d=++cnt;
    tr[d].l=merge(tr[x].l,tr[y].l);
    tr[d].r=merge(tr[x].r,tr[y].r);
    return d;
}
bool query(int d,int l,int r,int x,int y){
    if(!d)return ;
    if(l==x&&r==y)return ;
    int mid=l+r>>;
    if(x<=mid&&query(tr[d].l,l,mid,x,min(y,mid)))return ;
    if(y>mid&&query(tr[d].r,mid+,r,max(x,mid+),y))return ;
    return ;
}
void build(){
    for(int i=;i<=tot;++i)b[mx[i]]++;
    for(int i=;i<=tot;++i)b[i]+=b[i-];
    for(int i=tot;i>=;--i)c[b[mx[i]]--]=i;
    for(int i=tot;i>=;--i){
        ins(root[c[i]],,n,id[c[i]]);
        root[fa[c[i]]]=merge(root[fa[c[i]]],root[c[i]]);
    }
}
int main(){
    cin>>n;
    scanf("%s",s+);
    for(int i=;i<=n;++i)add(i,s[i]-'a');
    build();
    ans=;
    for(int i=;i<=tot;++i){
        int x=c[i];
        if(fa[x]==)dp[x]=,pos[x]=x;
        else if(query(root[pos[fa[x]]],,n,id[x]-mx[x]+mx[pos[fa[x]]],id[x]-)){dp[x]=dp[fa[x]]+;pos[x]=x;}
        else {dp[x]=dp[fa[x]];pos[x]=pos[fa[x]];}
        ans=max(ans,dp[x]);
    }
    cout<<ans;
    return ;
}