How Many Substrings?

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <vector>
#include <stack>
#include <queue>
#include <cmath>
#include <set>
#include <map>
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define link(x) for(edge *j=h[x];j;j=j->next)
#define inc(i,l,r) for(int i=l;i<=r;i++)
#define dec(i,r,l) for(int i=r;i>=l;i--)
const int MAXN=3e5+10;
const double eps=1e-8;
#define ll long long
using namespace std;
struct edge{int t,v;edge*next;}e[MAXN<<1],*h[MAXN],*o=e;
void add(int x,int y,int vul){o->t=y;o->v=vul;o->next=h[x];h[x]=o++;}
ll read(){
    ll x=0,f=1;char ch=getchar();
    while(!isdigit(ch)){if(ch==‘-‘)f=-1;ch=getchar();}
    while(isdigit(ch))x=x*10+ch-‘0‘,ch=getchar();
    return x*f;
}

int fa[MAXN],dis[MAXN],cnt,cur,ch[MAXN][26],n,m;
int Ch[MAXN][2],maxx[MAXN],pre[MAXN],flag[MAXN],Last[MAXN],key[MAXN];
bool rt[MAXN];
ll tag[MAXN<<2],sum[MAXN<<2];
void push_up(int x,int l,int r){
    if(!tag[x])return ;
    int mid=(l+r)>>1;
    tag[x<<1]+=tag[x];tag[x<<1|1]+=tag[x];
    sum[x<<1]+=1ll*(mid-l+1)*tag[x];
    sum[x<<1|1]+=1ll*(r-mid)*tag[x];
    tag[x]=0;
}
void update(int x,int l,int r,int ql,int qr,int t){
    if(ql<=l&&r<=qr){tag[x]+=t;sum[x]+=1ll*(r-l+1)*t;return ;}
    int mid=(l+r)>>1;
    push_up(x,l,r);
    if(ql<=mid)update(x<<1,l,mid,ql,qr,t);
    if(qr>mid)update(x<<1|1,mid+1,r,ql,qr,t);
    sum[x]=sum[x<<1]+sum[x<<1|1];
}
ll ans1;
void querty(int x,int l,int r,int ql,int qr){
    if(ql<=l&&r<=qr){ans1+=sum[x];return ;}
    int mid=(l+r)>>1;
    push_up(x,l,r);
    if(ql<=mid)querty(x<<1,l,mid,ql,qr);
    if(qr>mid)querty(x<<1|1,mid+1,r,ql,qr);
    sum[x]=sum[x<<1|1]+sum[x<<1];
}
void newnode(int x,int t){
    Ch[x][0]=Ch[x][1]=0;maxx[x]=key[x]=t;pre[x]=0;flag[x]=0;Last[x]=0;rt[x]=1;
}
void reverse(int x,int t){
    if(!x)return ;
    flag[x]=t;Last[x]=t;
}
void push(int x){
    if(flag[x]){
	reverse(Ch[x][0],flag[x]);
	reverse(Ch[x][1],flag[x]);
	flag[x]=0;
    }
}
void up(int x){maxx[x]=max(max(maxx[Ch[x][0]],maxx[Ch[x][1]]),key[x]);}

void P(int x){
    if(!rt[x])P(pre[x]);
    push(x);
}

void rotate(int x,int kind){
    int y=pre[x];
    pre[Ch[x][kind]]=y;Ch[y][!kind]=Ch[x][kind];
    if(rt[y])rt[y]=0,rt[x]=1;
    else Ch[pre[y]][Ch[pre[y]][1]==y]=x;
    pre[x]=pre[y];Ch[x][kind]=y;pre[y]=x;
    up(y);
}

void splay(int x){
    P(x);
    while(!rt[x]){
	if(rt[pre[x]])rotate(x,Ch[pre[x]][0]==x);
	else{
	    int y=pre[x];int kind=Ch[pre[y]][0]==y;
	    if(Ch[y][kind]==x)rotate(x,!kind),rotate(x,kind);
	    else rotate(y,kind),rotate(x,kind);
	}
    }
    up(x);
}

int find_root(int x){
    int t=x;
    while(Ch[t][0])t=Ch[t][0];
    return fa[t];
}

void calc(int x,int y,int l,int r){
    if(x)update(1,1,n,x-r+1,x-l,-1);
    update(1,1,n,y-r+1,y-l,1);
    return ;
}

void access(int x,int t){
    int y=0;
    while(x){
	splay(x);
	if(Ch[x][1])rt[Ch[x][1]]=1,pre[Ch[x][1]]=x,Ch[x][1]=0;
	up(x);
	if(y)rt[y]=0;
	int root=find_root(x);
	if(x!=1){calc(Last[x],t,key[root],maxx[x]);}
	Ch[x][1]=y;up(x);
	y=x;x=pre[x];
    }
    splay(1),reverse(1,t);
}
void Link(int x,int y){
    splay(x);pre[x]=y;
}
void destory(int x){
    splay(x);pre[Ch[x][0]]=pre[x];rt[Ch[x][0]]=1;
    Ch[x][0]=0;up(x);
}
void built(int x,int id){
    int last=cur;cur=++cnt;dis[cur]=dis[last]+1;int p=last;newnode(cur,dis[cur]);
    for(;p&&!ch[p][x];p=fa[p])ch[p][x]=cur;
    if(!p)fa[cur]=1,Link(cur,1);
    else{
	int q=ch[p][x];
	if(dis[p]+1==dis[q])fa[cur]=q,Link(cur,q);
	else{
	    int nt=++cnt;dis[nt]=dis[p]+1;newnode(nt,dis[nt]);
	    memcpy(ch[nt],ch[q],sizeof(ch[q]));
	    destory(q);Link(nt,fa[q]);
	    fa[nt]=fa[q];fa[q]=fa[cur]=nt;
	    Link(q,nt);Link(cur,nt);Last[nt]=Last[q];
	    for(;ch[p][x]==q;p=fa[p])ch[p][x]=nt;
	}
    }
}
char str[MAXN];
ll ans[MAXN];
typedef struct node{
    int l,id;
}node;
vector<node>vec[MAXN];
int main(){
    n=read();m=read();
    scanf("%s",str+1);
    int l,r;
    inc(i,1,m)l=read()+1,r=read()+1,vec[r].pb((node){l,i});
    cnt=cur=1;newnode(1,0);
    inc(i,1,n){
	built(str[i]-‘a‘,i);
	access(cur,i);
	for(int j=0;j<vec[i].size();j++)ans1=0,querty(1,1,n,vec[i][j].l,i),ans[vec[i][j].id]=ans1;
    }
    inc(i,1,m)printf("%lld\n",ans[i]);
    return 0;
}