Cod sursa(job #1377316)

Utilizator Corina1997Todoran Ana-Corina Corina1997 Data 5 martie 2015 21:10:06
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.04 kb
#include <fstream>
#include <vector>
#include <queue>
using namespace std;

ifstream is("bfs.in");
ofstream os("bfs.out");

void Bfs( int k );
int n, m, s;
int x, y;

#define INF 0x3f3f3f3f

vector<vector<int>> G;
vector<int> d;
vector<bool> S;
queue<int> Q;

int main()
{
    is >> n >> m >> s;
    G.resize(n+1);
    d = vector<int>(n+1, INF);
    S = vector<bool>(n+1);
    for ( int i = 1; i <= m; i++ )
    {
        is >> x >> y;
        G[x].push_back(y);
    }
    d[s] = 0;
    S[s] = true;
    Q.push(s);
    Bfs(s);
    for ( int i = 1; i <= n; i++ )
        if ( d[i] == INF )
            os << "-1 ";
        else
            os << d[i] << ' ';
    is.close();
    os.close();
    return 0;
}

void Bfs( int k )
{
    while(!Q.empty() )
    {
        k = Q.front();
        Q.pop();
        for( const auto& y : G[k] )
            if ( d[y] > d[k] + 1 && S[y] == false )
            {
                d[y] = d[k] + 1;
                Q.push(y);
                S[y] = true;
            }
    }

}