Submission #1093259

#	Time	Username	Problem	Language	Result	Execution time	Memory
1093259		alexander707070	Sequence (APIO23_sequence)	C++17	0 / 100	2090 ms	1266632 KiB

sequence

#include<bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#define MAXN 500007
using namespace std;

int n,a[MAXN],ans,c[MAXN];

vector<int> poss[MAXN];

const int bucket_sz=200;

struct node{
	int sum;
	int minpref,maxpref;

	inline friend node operator + (node fr,node sc){
		return {fr.sum+sc.sum,min(fr.minpref,fr.sum+sc.minpref),max(fr.maxpref,fr.sum+sc.maxpref)};
	}
}curr;

struct ST{
	node tree[4*MAXN];

	void update(int v,int l,int r,int pos,int val){
		if(l==r){
			tree[v].sum=val;
			tree[v].minpref=min(val,0);
			tree[v].maxpref=max(val,0);
		}else{
			int tt=(l+r)/2;
			if(pos<=tt)update(2*v,l,tt,pos,val);
			else update(2*v+1,tt+1,r,pos,val);

			tree[v]=tree[2*v]+tree[2*v+1];
		}
	}

	node getinfo(int v,int l,int r,int ll,int rr){
		if(ll>rr)return {0,0,0};
		if(l==ll and r==rr){
			return tree[v];
		}else{
			int tt=(l+r)/2;
			return getinfo(2*v,l,tt,ll,min(tt,rr)) + getinfo(2*v+1,tt+1,r,max(tt+1,ll),rr);
		}
	}
}seg;

struct ST2{

	struct node{
		int l,r,val;
	};

	vector<node> t;
	void init(){
		t.clear();

		t.push_back({0,0,10*n});
		t.push_back({0,0,10*n});
	}

	void addnode(){
		t.push_back({0,0,10*n});
	}

	void check(int v){
		if(t[v].l==0){
			addnode(); t[v].l=t.size()-1;
		}

		if(t[v].r==0){
			addnode(); t[v].r=t.size()-1;
		}
	}

	void update(int v,int l,int r,int pos,int val){
		if(l==r){
			t[v].val=min(val,t[v].val);
		}else{
			int tt=(l+r)/2;
			check(v);

			if(pos<=tt)update(t[v].l,l,tt,pos,val);
			else update(t[v].r,tt+1,r,pos,val);

			t[v].val=min(t[t[v].l].val,t[t[v].r].val);
		}
	}

	int getmin(int v,int l,int r,int ll,int rr){
		if(v==0 or ll>rr)return 10*n;
		if(l==ll and r==rr)return t[v].val;

		int tt=(l+r)/2;
		return min( getmin(t[v].l,l,tt,ll,min(tt,rr)) , getmin(t[v].r,tt+1,r,max(tt+1,ll),rr) );
	}
}segx[2*MAXN],segy[2*MAXN];

int solve(int val){

	int res=0;
	for(int ii=0;ii<poss[val].size();ii++){
		for(int ff=ii;ff<poss[val].size();ff++){
			int i=poss[val][ii];
			int f=poss[val][ff];

			int sum=seg.getinfo(1,1,n,i+1,f-1).sum;
			curr=seg.getinfo(1,1,n,f,n);
			int minpref=curr.minpref,maxpref=curr.maxpref;
			
			curr=seg.getinfo(1,1,n,1,i);
			int minsuff=curr.sum-curr.maxpref,maxsuff=curr.sum-curr.minpref;

			if((ff-ii+1)>=sum+minpref+minsuff and (ff-ii+1)>=-sum-maxpref-maxsuff)res=max(res,(ff-ii+1));
		}
	}

	return res;
}

struct event{
	int val,x,y;

	inline friend bool operator < (event fr,event sc){
		return fr.val<sc.val;
	}
};

set<event> xx,yy;

int A,B,C;

void incrx(){
	xx.insert({segx[B-(A-C)+n].getmin(1,0,2*n,0,B+(A-C)+n),B-(A-C)+n,B+(A-C)+n});
}

void incry(){
	yy.insert({segy[B+(A-C)+n].getmin(1,0,2*n,0,B-(A-C)+n),B-(A-C)+n,B+(A-C)+n});	
}

int mins(){
	while(!xx.empty()){
		auto it=xx.begin();
		event curr=*it;

		if(curr.x>B-(A-C)+n){
			xx.erase(it); continue;
		}

		if(curr.y>B+(A-C)+n){
			xx.erase(it); continue;
		}

		break;
	}

	while(!yy.empty()){
		auto it=yy.begin();
		event curr=*it;

		if(curr.x>B-(A-C)+n){
			yy.erase(it); continue;
		}

		if(curr.y>B+(A-C)+n){
			yy.erase(it); continue;
		}

		break;
	}

	int res=10*n;

	if(!xx.empty()){
		auto it=xx.begin();
		event s=*it; res=min(res,s.val);
	}

	if(!yy.empty()){
		auto it=yy.begin();
		event s=*it; res=min(res,s.val);
	}

	return res;
}

int bigsolve(int val){

	int res=0;
	A=B=C=0;

	xx.clear(); yy.clear();

	for(int i=0;i<=2*n;i++){
		segx[i].init(); segy[i].init();
	}

	segx[n].update(1,0,2*n,n,0);
	segy[n].update(1,0,2*n,n,0);

	for(int i=1;i<=n;i++){
		if(a[i]>val){
			A++;
			incry();
		}
		if(a[i]<val){
			C++;
			incrx();
		}

		if(a[i]==val){
			B++;
			incrx(); incry();
		}

		res=max(res,B-mins());
		
		segx[B-(A-C)+n].update(1,0,2*n,B+(A-C)+n,B);
		segy[B+(A-C)+n].update(1,0,2*n,B-(A-C)+n,B);
	}

	return res;
}

int sequence(int N, std::vector<int> A){
	n=N;
	for(int i=1;i<=n;i++){
		a[i]=A[i-1];
		poss[a[i]].push_back(i);

		seg.update(1,1,n,i,1);
	}

	for(int i=1;i<=n;i++){
		for(int f:poss[i-1])seg.update(1,1,n,f,-1);
		for(int f:poss[i])seg.update(1,1,n,f,0);

		if(poss[i].size()<=0)ans=max(ans,solve(i));
		else ans=max(ans,bigsolve(i));
	}

	return ans;
}

/*int main(){

	//cout<<sequence(9, {1, 1, 2, 3, 4, 3, 2, 1, 1})<<"\n";
	//cout<<sequence(14, {2, 6, 2, 5, 3, 4, 2, 1, 4, 3, 5, 6, 3, 2})<<"\n";
	
	return 0;
}*/

Compilation message (stderr)

sequence.cpp: In function 'int solve(int)':
sequence.cpp:105:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  105 |  for(int ii=0;ii<poss[val].size();ii++){
      |               ~~^~~~~~~~~~~~~~~~~
sequence.cpp:106:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |   for(int ff=ii;ff<poss[val].size();ff++){
      |                 ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 17
• Subtask 3: 0 / 7
• Subtask 4: 0 / 12
• Subtask 5: 0 / 13
• Subtask 6: 0 / 22
• Subtask 7: 0 / 18