Cod sursa(job #1748962)

Utilizator FredyLup Lucia Fredy Data 27 august 2016 15:58:07
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.07 kb
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream fin("bfs.in");
ofstream fout("bfs.out");

#define lim 100001
int N,M,S,x,y;
vector < vector<int> > a(lim);
vector <bool> selected(lim);
vector <int> path(lim);
queue <int> q;


void bfs()
{
    int act=S;
    q.push(S);
    selected[S]=true;
    path[act]=0;

    while(!q.empty())
    {
        act=q.front();
        selected[act]=true;

        for( vector<int>::iterator i=a[act].begin(); i<a[act].end(); i++)
            if(!selected[*i])
            {
                selected[*i]=true;
                path[*i]=path[act]+1;
                q.push( *i );
            }

        q.pop();
    }

}


int main()
{
    fin>>N>>M>>S;

    for(int i=1; i<=M; i++)
    {
        fin>>x>>y;
        a[x].push_back(y);
    }

    bfs();

    for (int i = 1; i <=N ; ++i )
    {
        if ( selected[i] )
            fout << path[i] << ' ';
        else
            fout << -1 << ' ';
    }


    fin.close();
    fout.close();
    return 0;
}