Submission #129828

#	Time	Username	Problem	Language	Result	Execution time	Memory
129828		davitmarg	Portals (BOI14_portals)	C++17	100 / 100	994 ms	140740 KiB

portals

/*DavitMarg*/
#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <queue>
#include <iomanip>
#include <stack>
#include <cassert>
#include <iterator>
#include <bitset>
#include <fstream>
#define mod 1000000007ll
#define LL long long
#define LD long double
#define MP make_pair
#define PB push_back
#define all(v) v.begin(),v.end()
using namespace std;

int n,m,k,st,en;
vector<bool> used;
int u[1003][1003],d[1003][1003],l[1003][1003],r[1003][1003];
vector<pair<int,int>> g[1010006];
vector<int> dist;
char a[1003][1003];

int id(int y,int x)
{
	return y*m+x;
}

void print(int ind)
{
	int y,x;
    x=ind%m;
    if(!x)
		x=m;
    y=(ind-x)/m;
    cout<<"! "<<y<<" "<<x<<" d="<<dist[ind]<<endl;
}

void addNode(int a,int b,int d)
{
	g[a].PB(MP(b,d));
}

int main()
{
    cin >> n >> m;
    k=(m+1)*(n+1);
    dist.resize(k+5);
    used.resize(k+5);
    for(int i=1;i<=n;i++)
	{
		int x=getchar();
		for(int j=1;j<=m;j++)
		{
            x=getchar();
            a[i][j]=(char)x;
            if(a[i][j]=='S')
			{
				st=id(i,j);
                a[i][j]='.';
			}
			else if(a[i][j]=='C')
			{
				en=id(i,j);
                a[i][j]='.';
			}
		}
	}
    for(int i=1;i<=n;i++)
        a[i][0]=a[i][m+1]='#';
    for(int i=1;i<=m;i++)
        a[0][i]=a[n+1][i]='#';


    for(int i=0;i<=n;i++)
		for(int j=0;j<=m;j++)
		{
            if(a[i][j]=='#')
			{
                u[i][j]=id(i+1,j);
                l[i][j]=id(i,j+1);
			}
			else
			{
				u[i][j]=u[i-1][j];
				l[i][j]=l[i][j-1];
			}
		}

    for(int i=n+1;i>=1;i--)
		for(int j=m+1;j>=1;j--)
		{
            if(a[i][j]=='#')
			{
                d[i][j]=id(i-1,j);
                r[i][j]=id(i,j-1);
			}
			else
			{
				d[i][j]=d[i+1][j];
				r[i][j]=r[i][j+1];
			}
		}
    queue<int> Q;

    for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
            if(a[i][j]!='#' && a[i-1][j]=='#' || a[i+1][j]=='#' || a[i][j-1]=='#'|| a[i][j+1]=='#')
			{
				int start=id(i,j);
				Q.push(start);
				used[start]=1;
			}

    for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
		{
			if(a[i][j]=='#')
                continue;
            if(a[i-1][j]!='#')
                addNode(id(i,j),id(i-1,j),1);
            if(a[i+1][j]!='#')
                addNode(id(i,j),id(i+1,j),1);
            if(a[i][j-1]!='#')
                addNode(id(i,j),id(i,j-1),1);
            if(a[i][j+1]!='#')
                addNode(id(i,j),id(i,j+1),1);
		}

    while(!Q.empty())
	{
		int v=Q.front();
        Q.pop();
        //print(v);
        for(int i=0;i<g[v].size();i++)
		{
			int to=g[v][i].first;
            if(used[to])
				continue;
			used[to]=1;
            dist[to]=dist[v]+1;
            Q.push(to);
		}
	}


    for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
		{
			if(a[i][j]=='#')
                continue;
            if(1)
			{
				addNode(id(i,j),u[i][j],dist[id(i,j)]+1);
				addNode(id(i,j),d[i][j],dist[id(i,j)]+1);
				addNode(id(i,j),l[i][j],dist[id(i,j)]+1);
				addNode(id(i,j),r[i][j],dist[id(i,j)]+1);
			}
		}

    for(int i=1;i<=k;i++)
	{
		used[i]=0;
        dist[i]=mod;
	}

    priority_queue<pair<int,int>> q;
    q.push(MP(0,st));
    dist[st]=0;
    int ans=0;
    while(!q.empty())
	{
        int v=-1;
        int now=0;
        do
		{
			v=q.top().second;
			now=q.top().first;
            q.pop();
		}while(used[v] && !q.empty());

        if(used[v]==1 && v==-1)
            break;
        used[v]=1;
		if(v==en)
		{
            ans=-now;
			break;
		}
		for(int i=0;i<g[v].size();i++)
		{
            int to=g[v][i].first;
            int D=g[v][i].second;
            if(!used[to])
			{
                q.push(MP(-(D-now),to));
			}
		}
	}

	cout<<ans<<endl;

    return 0;
}


/*

15 10
.....C....
..........
..........
..........
..........
..........
..........
...S......
..........
..........
..........
..........
..........
..........
..........


*/

Compilation message (stderr)

portals.cpp: In function 'int main()':
portals.cpp:116:29: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
             if(a[i][j]!='#' && a[i-1][j]=='#' || a[i+1][j]=='#' || a[i][j-1]=='#'|| a[i][j+1]=='#')
                ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
portals.cpp:143:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<g[v].size();i++)
                     ~^~~~~~~~~~~~
portals.cpp:198:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<g[v].size();i++)
               ~^~~~~~~~~~~~

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