Submission #145028

#	Time	Username	Problem	Language	Result	Execution time	Memory
145028		TadijaSebez	Rectangles (IOI19_rect)	C++14	100 / 100	4056 ms	809504 KiB

rect

#include "rect.h"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mt make_tuple
#define pb push_back
const int N=2505;
const int M=2*N;
const int inf=1e9+7;
int a[N][N],n,m,U1[N][N],D1[N][N],L1[N][N],R1[N][N],U2[N][N],D2[N][N],L2[N][N],R2[N][N],S[N],c,tmp[N];
struct SegmentTreeMax
{
	int mx[M];
	SegmentTreeMax(){ for(int i=0;i<M;i++) mx[i]=-inf;}
	void Build(int a[])
	{
		for(int i=0;i<N;i++) mx[i+N]=a[i];
		for(int i=N-1;i;i--) mx[i]=max(mx[i<<1],mx[i<<1|1]);
	}
	void Set(int i, int f){ for(i+=N;i;i>>=1) mx[i]=max(mx[i],f);}
	int Get(int l, int r)
	{
		int ans=-inf;
		for(l+=N,r+=N;l<=r;l>>=1,r>>=1)
		{
			if(l%2==1) ans=max(ans,mx[l++]);
			if(r%2==0) ans=max(ans,mx[r--]);
		}
		return ans;
	}
} RMX[N],CMX[N];
struct SegmentTreeMin
{
	int mn[M];
	SegmentTreeMin(){ for(int i=0;i<M;i++) mn[i]=inf;}
	void Build(int a[])
	{
		for(int i=0;i<N;i++) mn[i+N]=a[i];
		for(int i=N-1;i;i--) mn[i]=min(mn[i<<1],mn[i<<1|1]);
	}
	void Set(int i, int f){ for(i+=N;i;i>>=1) mn[i]=min(mn[i],f);}
	int Get(int l, int r)
	{
		int ans=inf;
		for(l+=N,r+=N;l<=r;l>>=1,r>>=1)
		{
			if(l%2==1) ans=min(ans,mn[l++]);
			if(r%2==0) ans=min(ans,mn[r--]);
		}
		return ans;
	}
} RMN[N],CMN[N];
void Build()
{
	for(int i=1;i<=n;i++)
	{
		S[c=0]=0;
		for(int j=1;j<=m;j++)
		{
			while(c && a[i][S[c]]<=a[i][j]) c--;
			L1[i][j]=S[c];S[++c]=j;
		}
		S[c=0]=m+1;
		for(int j=m;j>=1;j--)
		{
			while(c && a[i][S[c]]<=a[i][j]) c--;
			R1[i][j]=S[c];S[++c]=j;
		}
		S[c=0]=0;
		for(int j=1;j<=m;j++)
		{
			while(c && a[i][S[c]]<a[i][j]) c--;
			L2[i][j]=S[c];S[++c]=j;
		}
		S[c=0]=m+1;
		for(int j=m;j>=1;j--)
		{
			while(c && a[i][S[c]]<a[i][j]) c--;
			R2[i][j]=S[c];S[++c]=j;
		}
	}
	for(int j=1;j<=m;j++)
	{
		S[c=0]=0;
		for(int i=1;i<=n;i++)
		{
			while(c && a[S[c]][j]<=a[i][j]) c--;
			U1[i][j]=S[c];S[++c]=i;
		}
		S[c=0]=n+1;
		for(int i=n;i>=1;i--)
		{
			while(c && a[S[c]][j]<=a[i][j]) c--;
			D1[i][j]=S[c];S[++c]=i;
		}
		S[c=0]=0;
		for(int i=1;i<=n;i++)
		{
			while(c && a[S[c]][j]<a[i][j]) c--;
			U2[i][j]=S[c];S[++c]=i;
		}
		S[c=0]=n+1;
		for(int i=n;i>=1;i--)
		{
			while(c && a[S[c]][j]<a[i][j]) c--;
			D2[i][j]=S[c];S[++c]=i;
		}
	}
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=m;j++) tmp[j]=U2[i][j];
		RMX[i].Build(tmp);
		for(int j=1;j<=m;j++) tmp[j]=D2[i][j];
		RMN[i].Build(tmp);
	}
	for(int j=1;j<=m;j++)
	{
		for(int i=1;i<=n;i++) tmp[i]=L2[i][j];
		CMX[j].Build(tmp);
		for(int i=1;i<=n;i++) tmp[i]=R2[i][j];
		CMN[j].Build(tmp);
	}
}
/*struct Rectangle
{
	int x1,y1,x2,y2;
	Rectangle(){}
	Rectangle(int a, int b, int c, int d):x1(a),y1(b),x2(c),y2(d){}
	bool operator == (Rectangle b){ return mt(x1,y1,x2,y2)==mt(b.x1,b.y1,b.x2,b.y2);}
	bool operator < (Rectangle b){ return mt(x1,y1,x2,y2)<mt(b.x1,b.y1,b.x2,b.y2);}
};*/
//vector<Rectangle> work;
vector<pair<int,int>> work[N][N];
void Try(int x, int y)
{
	if(L1[x][y]!=0 && R1[x][y]!=m+1 && U1[x][y]!=0 && D1[x][y]!=n+1)
	{
		int x1=U1[x][y];
		int y1=L1[x][y];
		int x2=D1[x][y];
		int y2=R1[x][y];
		//work.pb(Rectangle(x1,y1,x2,y2));
		work[x1][y1].pb({x2,y2});
	}
}
bool was[N][N];
ll Solve()
{
	Build();
	for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) Try(i,j);
	//sort(work.begin(),work.end());
	//work.resize(unique(work.begin(),work.end())-work.begin());
	ll ans=0;
	for(int x1=1;x1<=n;x1++)
	{
		for(int y1=1;y1<=m;y1++)
		{
			for(auto p:work[x1][y1])
			{
				int x2,y2;
				tie(x2,y2)=p;
				if(was[x2][y2]) continue;
				was[x2][y2]=1;
				int ok=0;
				if(RMN[x1].Get(y1+1,y2-1)>=x2) ok++;
				if(RMX[x2].Get(y1+1,y2-1)<=x1) ok++;
				if(CMN[y1].Get(x1+1,x2-1)>=y2) ok++;
				if(CMX[y2].Get(x1+1,x2-1)<=y1) ok++;
				if(ok==4) ans++;
			}
			for(auto p:work[x1][y1])
			{
				int x2,y2;
				tie(x2,y2)=p;
				was[x2][y2]=0;
			}
		}
	}
	/*for(Rectangle r:work)
	{
		int x1,y1,x2,y2;
		tie(x1,y1,x2,y2)=mt(r.x1,r.y1,r.x2,r.y2);
		int ok=0;
		if(RMN[x1].Get(y1+1,y2-1)>=x2) ok++;
		if(RMX[x2].Get(y1+1,y2-1)<=x1) ok++;
		if(CMN[y1].Get(x1+1,x2-1)>=y2) ok++;
		if(CMX[y2].Get(x1+1,x2-1)<=y1) ok++;
		if(ok==4) ans++;
	}*/
	return ans;
}
ll count_rectangles(vector<vector<int> > a)
{
	n=a.size();m=a[0].size();
	for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) ::a[i][j]=a[i-1][j-1];
	return Solve();
}

• Subtask 1: 8 / 8
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 22 / 22
• Subtask 5: 10 / 10
• Subtask 6: 13 / 13
• Subtask 7: 28 / 28