Submission #26191

#	Time	Username	Problem	Language	Result	Execution time	Memory
26191		samir_droubi	Portals (BOI14_portals)	C++14	70 / 100	1000 ms	51716 KiB

portals

#include <bits/stdc++.h>
using namespace std;
const int mxn=1005;
int n,m;
char g[mxn][mxn];

int dx[]={0,0,1,-1};
int dy[]={1,-1,0,0};
bool check(int x,int y){
	return x>=1&&x<=n&&y>=1&&y<=m&&g[x][y]!='#';
}

int wall[mxn][mxn];
queue<pair<int,int> >q;
void bfs()
{
	while(!q.empty())
	{
		int x=q.front().first;
		int y=q.front().second;
		q.pop();
		for(int i=0;i<4;++i)
		{
			int xx=x+dx[i];
			int yy=y+dy[i];
			if(!check(xx,yy))continue;
			if(wall[xx][yy]>wall[x][y]+1)
			{
				wall[xx][yy]=wall[x][y]+1;
				q.push({xx,yy});
			}
		}
	}
}

set<int>r[mxn];
set<int>c[mxn];
int left(int x,int y)
{
	set<int>::iterator it=r[x].lower_bound(y);
	--it;
	return *it + 1;
}
int right(int x,int y)
{
	set<int>::iterator it=r[x].lower_bound(y);
	return *it - 1;
}
int up(int x,int y)
{
	set<int>::iterator it=c[y].lower_bound(x);
	--it;
	return *it + 1;
}
int down(int x,int y)
{
	set<int>::iterator it=c[y].lower_bound(x);
	return *it - 1;
}

int dist[mxn][mxn];
set<pair<int,pair<int,int> > >pq;
void dijkstra(int x,int y)
{
	dist[x][y]=0;
	pq.insert({0,{x,y}});
	while(!pq.empty())
	{
		pair<int,pair<int,int> > p=*pq.begin();
		pq.erase(pq.begin());
		int ds=p.first;
		int x=p.second.first;
		int y=p.second.second;

		for(int i=0;i<4;++i)
		{
			int xx=x+dx[i];
			int yy=y+dy[i];
			if(!check(xx,yy))continue;
			if(dist[xx][yy]>ds+1)
			{
				dist[xx][yy]=ds+1;
				pq.insert({dist[xx][yy],{xx,yy}});
			}
		}
		
		int xx,yy;
		yy=left(x,y);
		if(dist[x][yy]>ds+wall[x][y])
		{
			dist[x][yy]=ds+wall[x][y];
			pq.insert({dist[x][yy],{x,yy}});	
		}

		yy=right(x,y);
		if(dist[x][yy]>ds+wall[x][y])
		{
			dist[x][yy]=ds+wall[x][y];
			pq.insert({dist[x][yy],{x,yy}});	
		}

		xx=up(x,y);
		if(dist[xx][y]>ds+wall[x][y])
		{
			dist[xx][y]=ds+wall[x][y];
			pq.insert({dist[xx][y],{xx,y}});	
		}

		xx=down(x,y);
		if(dist[xx][y]>ds+wall[x][y])
		{
			dist[xx][y]=ds+wall[x][y];
			pq.insert({dist[xx][y],{xx,y}});	
		}		
	}
}

void clear()
{
	for(int i=0;i<mxn;++i)
		for(int j=0;j<mxn;++j)
		{
			wall[i][j]=(1e9);
			dist[i][j]=(1e9);
		}
}
int main()
{
	clear();

	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;++i)
		for(int j=1;j<=m;++j)
			cin>>g[i][j];

	for(int i=1;i<=n;++i)
		for(int j=1;j<=m;++j)
		{
			bool ok=false;
			for(int k=0;k<4;++k)
			{
				int x=i+dx[k];
				int y=j+dy[k];
				if(!check(x,y))ok=true;
			}
			if(ok)
			{
				wall[i][j]=1;
				q.push({i,j});
			}
		}	

	bfs();

	for(int i=1;i<=n;++i)
		for(int j=1;j<=m;++j)
			if(g[i][j]=='#')
			{
				r[i].insert(j);
				c[j].insert(i);
			}
	for(int i=1;i<=n;++i)
	{
		r[i].insert(0);
		r[i].insert(m+1);
	}
	for(int i=1;i<=m;++i)
	{
		c[i].insert(0);
		c[i].insert(n+1);
	}

	for(int i=1;i<=n;++i)
		for(int j=1;j<=m;++j)
			if(g[i][j]=='S')dijkstra(i,j);

	for(int i=1;i<=n;++i)
		for(int j=1;j<=m;++j)
			if(g[i][j]=='C')printf("%d\n",dist[i][j]);
	return 0;	

}

Compilation message (stderr)

portals.cpp: In function 'int main()':
portals.cpp:131:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
                     ^

• Subtask 1: 11 / 11
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 19 / 19
• Subtask 5: 0 / 30