Submission #1093195

#	Time	Username	Problem	Language	Result	Execution time	Memory
1093195		alexander707070	Sequence (APIO23_sequence)	C++17	41 / 100	2081 ms	841700 KiB

sequence

#include<bits/stdc++.h>
#define MAXN 500007
using namespace std;

int n,a[MAXN],ans,c[MAXN];
int pref[MAXN],mins[MAXN],maxs[MAXN];

vector<int> poss[MAXN];

const int bucket_sz=500;

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 ST2D{
	struct node{
		int l,r,val;
	};

	struct ST1D{
		vector<node> tree;

		void init(){
			tree.clear();

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

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

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

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

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

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

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

		int getmin(int v,int l,int r,int ll,int rr){
			if(ll>rr)return n;
			if(l==ll and r==rr)return tree[v].val;

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

	ST1D tree[8*MAXN];

	void init(){
		for(int i=1;i<=8*n;i++)tree[i].init();
	}

	void update(int v,int l,int r,int posx,int posy,int val){
		if(l==r){
			tree[v].update(1,0,2*n,posy,val);
		}else{
			int tt=(l+r)/2;

			if(posx<=tt)update(2*v,l,tt,posx,posy,val);
			else update(2*v+1,tt+1,r,posx,posy,val);

			tree[v].update(1,0,2*n,posy,val);
		}
	}

	int getmin(int v,int l,int r,int lx,int rx,int ly,int ry){
		if(lx>rx)return 10*n;
		if(l==lx and r==rx)return tree[v].getmin(1,0,2*n,ly,ry);

		int tt=(l+r)/2;
		return min( getmin(2*v,l,tt,lx,min(tt,rx),ly,ry) , getmin(2*v+1,tt+1,r,max(tt+1,lx),rx,ly,ry) );
	}
}seg2;

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;
}

int bigsolve(int val){
	seg2.init();

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

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

		res=max(res,B-seg2.getmin(1,0,2*n,0,B-(A-C)+n,0,B+(A-C)+n));
		seg2.update(1,0,2*n,B-(A-C)+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()<=bucket_sz)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:132:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  132 |  for(int ii=0;ii<poss[val].size();ii++){
      |               ~~^~~~~~~~~~~~~~~~~
sequence.cpp:133:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  133 |   for(int ff=ii;ff<poss[val].size();ff++){
      |                 ~~^~~~~~~~~~~~~~~~~

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