【BZOJ】【P2453】【维护队列】【题解】【树套树】

传送门:http://www.lydsy.com:808/JudgeOnline/problem.php?id=2453

一句话,区间不重复元素个数,如果颜色少的话可以状压,颜色多的话维护每种颜色的pre值,询问[l,r]也就是询问区间中<l的pre个数

Code:

#include<bits/stdc++.h>#define rnd() ((rand()<<16)|rand())using namespace std;const int maxn=1e5+10;map<int,int>M,mp;set<int>S[maxn<<1];int pre[maxn],nxt[maxn],n,m,a[maxn];struct Treap{struct node;node *root,*Null;struct node{int val,key,size,s;node *c[2];void set(int _val,node *C){val=_val;key=rnd();c[0]=c[1]=C;size=s=1;}node *rz(){size=c[0]->size+c[1]->size+s;return this;}};Treap(){Null=new node();Null->set(INT_MIN,Null);Null->key=INT_MAX;Null->size=Null->s=0;root=Null;}void rot(node *&t,bool d){node *p=t->c[d];t->c[d]=p->c[!d];p->c[!d]=t;t->rz();p->rz();t=p;}void _insert(node *&t,int x){if(t==Null){t=new node();t->set(x,Null);return;}if(t->val==x){t->size++;t->s++;return;}_insert(t->c[x>t->val],x);if(t->c[x>t->val]->key<t->key)rot(t,x>t->val);else t->rz();}void _del(node *&t,int x){if(t==Null)return;if(t->val==x){if(t->s>1){t->size--;t->s--;return;}bool d=t->c[0]->key>t->c[1]->key;if(t->c[d]==Null){delete t;t=Null;return;}rot(t,d);_del(t->c[!d],x);}else _del(t->c[x>t->val],x);t->rz();}int _rank(node *t,int x){if(t==Null)return 0;int r=t->c[0]->size;if(t->val>x)return _rank(t->c[0],x);if(t->val==x)return r;if(t->val<x)return r+t->s+_rank(t->c[1],x);}int size(){return root->size;}void insert(int x){return _insert(root,x);}void del(int x){return _del(root,x);}int rank(int x){return _rank(root,x);}};struct seg_tree{Treap t[maxn<<2];#define lson i<<1,l,mid#define rson i<<1|1,mid+1,r#define L i<<1#define R i<<1|1void build(int i,int l,int r){for(int o=l;o<=r;o++)t[i].insert(pre[o]);if(l==r)return;int mid=(l+r)>>1;build(lson);build(rson);}void Change(int i,int l,int r,int pos,int val,int x){t[i].del(val);t[i].insert(x);if(l==r)return;int mid=(l+r)>>1;if(pos<=mid)Change(lson,pos,val,x);else Change(rson,pos,val,x);}int Query(int i,int l,int r,int l0,int r0){if(l0<=l&&r0>=r){int deb=t[i].rank(l0);return deb;}int mid=(l+r)>>1,ans=0;if(l0<=mid)ans+=Query(lson,l0,r0);if(r0>mid)ans+=Query(rson,l0,r0);return ans;}#undef R}T;int tot=0;void Q(int l,int r){printf("%d\n",T.Query(1,1,n,l,r));}void R(int pos,int val){if(!mp[val])mp[val]=++tot,S[tot].insert(0);int x=mp[val],y=mp[a[pos]];a[pos]=val;set<int>::iterator it1,it2;it1=--S[y].lower_bound(pos);it2=S[y].upper_bound(pos);if(it2!=S[y].end()){T.Change(1,1,n,*it2,pre[*it2],*it1);pre[*it2]=*it1;}S[y].erase(pos);S[x].insert(pos);it1=--S[x].lower_bound(pos);it2=S[x].upper_bound(pos);T.Change(1,1,n,pos,pre[pos],*it1);pre[pos]=*it1;if(it2!=S[x].end()){T.Change(1,1,n,*it2,pre[*it2],pos);pre[*it2]=pos;}}int main(){srand(10086);scanf("%d%d",&n,&m);for(int i=1;i<=n;i++)scanf("%d",&a[i]);for(int i=1;i<=n;i++){if(!mp[a[i]])mp[a[i]]=++tot,S[tot].insert(0);pre[i]=M[a[i]];M[a[i]]=i;S[mp[a[i]]].insert(i);}M.clear();T.build(1,1,n);while(m--){char op=getchar();while(op!='Q'&&op!='R')op=getchar();int l,r;scanf("%d%d",&l,&r);if(op=='Q'){Q(l,r);}else{R(l,r);}}return 0;}