Luogu3732 [HAOI2017] 供给侧改革 【后缀数组】【线段树】【乱搞】

题目分析：

这道题我是乱搞的，因为他说$01$串是随机的。

那么我们可以猜测能够让LCP变大的地方很少。求出后缀数组之后可能让LCP变大的地方就等价于从大到小往height里动态加点同时维护这个点左右两边的单调栈。

这个事情用线段树模拟就行了。

用暴力跑一下发现果然不大，只有200w，其中很多还是废点，把废点特判一下删除掉就行了。

然后把询问离线，按r排序，再作扫描线，每次扫到r的时候把前面变动的LCP更新一下。然后对于询问也做一个类似上面单调栈的操作。

代码：

 #include<bits/stdc++.h>
 #define RI register
 using namespace std;

 const int maxn = ;
 const int N = ;

 int n,q;
 char str[maxn];
 int T[maxn<<],a[maxn];
 int RMQ[maxn][],pw[maxn];

 struct node{int l,r,nb;}qy[maxn];
 int ans[maxn];
 int sa[maxn],rk[maxn],X[maxn],Y[maxn];
 int ht[maxn],h[maxn];

 void fstread(int &x){
     char ch = getchar();x = ;
     while(ch > '' || ch < '') ch = getchar();
     while(ch >= '' && ch <= '') x = x*+ch-'',ch=getchar();
 }

 int chk(int x,int k){
     return rk[sa[x]]==rk[sa[x-]]&&rk[sa[x]+(<<k)]==rk[sa[x-]+(<<k)];
 }

 void GetSA(){
     for(RI int i=;i<n;i++) X[str[i]]++;
     for(RI int i=;i<=N;i++) X[i] += X[i-];
     for(RI int i=n-;i>=;i--) sa[X[str[i]]--] = i;
     for(RI int i = , num = ;i <= n;i++)
     rk[sa[i]] = (str[sa[i]] == str[sa[i-]]?num:++num);
     rk[sa[]] = ;
     for(int k=;(<<k-)<=n;k++){
     for(RI int i=;i<=N;i++) X[i] = ;
     for(RI int i=n-(<<k-);i<n;i++) Y[i-n+(<<k-)+]=i;
     for(RI int i=,j=(<<k-)+;i<=n;i++)
         if(sa[i]>=(<<k-))Y[j++]=sa[i]-(<<k-);
     for(RI int i=;i<n;i++) X[rk[i]]++;
     for(RI int i=;i<=N;i++) X[i]+=X[i-];
     for(RI int i=n;i>=;i--) sa[X[rk[Y[i]]]--] = Y[i];
     int num = ; Y[sa[]] = ;
     for(RI int i=;i<=n;i++) Y[sa[i]] = (chk(i,k-)?num:++num);
     for(RI int i=;i<n;i++) rk[i] = Y[i];
     if(num == n) break;
     }
 }

 void buildRMQ(){
     for(int i=;i<=n;i++) RMQ[i][] = ht[i];
     for(int i=;(<<i)<=n;i++) pw[(<<i)] = i;
     for(int i=;i<=n;i++) if(!pw[i]) pw[i] = pw[i-];
     for(int k=;(<<k)<=n;k++){
     for(RI int i=;i<=n;i++){
         if(i+(<<k-)>n) RMQ[i][k] = RMQ[i][k-];
         else RMQ[i][k] = min(RMQ[i][k-],RMQ[i+(<<k-)][k-]);
     }
     }
 }

 void GetHeight(){
     for(RI int i=;i<n;i++){
     if(i) h[i] = max(,h[i-]-);
     if(rk[i] == ) {h[i] = ;continue;}
     while(str[i+h[i]] == str[sa[rk[i]-]+h[i]]) h[i]++;
     }
     for(RI int i=;i<n;i++) ht[rk[i]] = h[i];
 }

 int LCP(int l,int r){
     l = rk[l],r = rk[r]; if(l > r) swap(l,r);l++;
     int k = pw[r-l+];
     return min(RMQ[l][k],RMQ[r-(<<k)+][k]);
 }

 void update(int now,int tl,int tr,int pos,int len){
     if(tl == tr){T[now] = max(T[now],len); return;}
     int mid = (tl+tr)/;
     if(pos <= mid) update(now<<,tl,mid,pos,len);
     else update(now<<|,mid+,tr,pos,len);
     T[now] = max(T[now<<],T[now<<|]);
 }

 int Query(int now,int tl,int tr,int l,int r,int mx){
     if(tl >= l && tr <= r){
     if(T[now] <= mx) return -;
     else{
         while(tl < tr){
         int mid = (tl+tr)/;
         if(T[now<<|] > mx) tl = mid+,now = now*+;
         else tr = mid,now<<=;
         }
         return tl;
     }
     }
     if(tl > r || tr < l) return -;
     int mid = (tl+tr)/;
     if(mid >= r) return Query(now<<,tl,mid,l,r,mx);
     if(mid < l) return Query(now<<|,mid+,tr,l,r,mx);
     int z = Query(now<<|,mid+,tr,l,r,mx);
     if(z!=-) return z;
     else return Query(now<<,tl,mid,l,r,mx);
 }

 vector<int> mlgb[maxn];

 namespace BruteForce{
     int minn[maxn<<];

     pair<int,int> QueryRange(int now,int tl,int tr,int l,int r,int up,int d){
     if(tl >= l && tr <= r && d == ){
         if(minn[now] < up){
         while(tl != tr){
             int mid = (tl+tr)/;
             if(minn[now<<|] < up) tl = mid+,now=now*+;
             else tr = mid,now<<=;
         }
         return make_pair(minn[now],tl);
         }else return make_pair(,);
     }
     if(tl >= l && tr <= r && d == ){
         if(minn[now] < up){
         while(tl != tr){
             int mid = (tl+tr)/;
             if(minn[now<<] < up) tr = mid,now<<=;
             else tl = mid+,now=now*+;
         }
         return make_pair(minn[now],tl);
         }else return make_pair(,);
     }
     if(tl > r || tr < l) return make_pair(,);
     int mid = (tl+tr)/;
     if(mid>=r) return QueryRange(now<<,tl,mid,l,r,up,d);
     if(mid<l) return QueryRange(now<<|,mid+,tr,l,r,up,d);
     if(d){
         pair<int,int> z = QueryRange(now<<|,mid+,tr,l,r,up,d);
         if(z.first) return z;
         else return QueryRange(now<<,tl,mid,l,r,up,d);
     }else{
         pair<int,int> z = QueryRange(now<<,tl,mid,l,r,up,d);
         if(z.first) return z;
         else return QueryRange(now<<|,mid+,tr,l,r,up,d);
     }
     }
     void add(int now,int tl,int tr,int pos,int dt){
     if(tl == tr) {minn[now] = dt;return;}
     int mid = (tl+tr)/;
     if(pos <= mid) add(now<<,tl,mid,pos,dt);
     else add(now<<|,mid+,tr,pos,dt);
     minn[now] = min(minn[now<<],minn[now<<|]);
     }

     void holyshit(){
     memset(minn,0x3f,sizeof(minn));
     for(int i=n-;i>=;i--){
         int z = rk[i],p=;
         add(,,n,z,i);
         while(true){
         pair<int,int> um = QueryRange(,,n,z+,n,p,);
         if(!um.first) break;
         mlgb[um.first].push_back(i);
         z = um.second; p = sa[z];
         }
         z = rk[i],p = ;
         while(true){
         pair<int,int> um = QueryRange(,,n,,z-,p,);
         if(!um.first) break;
         mlgb[um.first].push_back(i);
         z = um.second; p = sa[z];
         }
     }

     }
 }

 void work(){
     GetSA();
     GetHeight();
     buildRMQ();

     BruteForce::holyshit();
     int num = ;
     for(int i=;i<n;i++){
     for(int j=;j<mlgb[i].size();j++){
         int z = LCP(mlgb[i][j],i);
         if(a[mlgb[i][j]] >= z) continue;
         a[mlgb[i][j]] = z;
         update(,,n-,mlgb[i][j],z);

     }
     while(qy[num].r == i){
         int z = ,pq = qy[num].r-;
         while(pq >= qy[num].l){
         int hp = Query(,,n-,,pq,z);
         if(hp < qy[num].l) hp = qy[num].l-;
         ans[qy[num].nb] += (pq-hp)*z;
         if(hp < ) break;
         z = a[hp],pq = hp;
         }
         num++;
     }
     }
     for(int i=;i<=q;i++) printf("%d\n",ans[i]);
 }

 int cmp(node alpha,node beta){return alpha.r < beta.r;}
 int main(){
     //freopen("1.in","r",stdin);
     fstread(n);fstread(q);
     for(int i=;i<=n;i++){
     str[i-] = getchar();
     while(str[i-]!= '' && str[i-] != '') str[i-] = getchar();
     }
     for(int i=;i<=q;i++) fstread(qy[i].l),fstread(qy[i].r),qy[i].nb=i;
     for(int i=;i<=q;i++) qy[i].l--,qy[i].r--;
     sort(qy+,qy+q+,cmp);
     work();
     return ;
 }