Cod sursa(job #435251)

Utilizator alexandru92alexandru alexandru92 Data 7 aprilie 2010 09:30:31
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.82 kb
/* 
 * File:   main.cpp
 * Author: SpeeDemon
 *
 * Created on April 7, 2010, 9:18 AM
 */
#include <queue>
#include <cstdlib>
#include <fstream>
#include <iterator>

/*
 * 
 */
using namespace std;
typedef pair< int, int > pr;
vector< int > d, howmuch;
vector< bool > inH;
vector< vector< pr > > G;
vector< pr >::const_iterator it, iend;
class cmp
{
public :
    inline bool operator() ( const int& x, const int& y ) const
    {
        return d[x] > d[y];
    }
};
priority_queue< int, vector<int>, cmp > H;
int main(int argc, char** argv)
 {
    int N, M, x, y, c;
    ifstream in( "bellmanford.in" );
    in>>N>>M;
    G.resize(N);
    for( ; M; --M )
    {
        in>>x>>y>>c;
        --x, --y;
        G[x].push_back( pr( y, c ) );
    }
    d.resize(N);
    inH.resize(N);
    howmuch.resize(N);
    for( H.push(0); !H.empty(); )
    {
        x=H.top(); H.pop();
        inH[x]=false;
        for( it=G[x].begin(), iend=G[x].end(); it < iend; ++it )
        {
            y=it->first; c=it->second;
            if( !howmuch[y] )
            {
                d[y]=d[x]+c;
                H.push(y);
                inH[y]=true;
                howmuch[y]=1;
                continue;
            }
            if( d[y] > d[x]+c )
            {
                d[y]=d[x]+c;
                if( !inH[y] )
                {
                    H.push(y);
                    inH[y]=true;
                    ++howmuch[y];
                    if( howmuch[y] > N )
                    {
                        ofstream out( "bellmanford.out" );
                        out<<"Ciclu negativ!";
                        return EXIT_SUCCESS;
                    }
                }
            }
        }
    }
    ofstream out( "bellmanford.out" );
    copy( d.begin()+1, d.end(), ostream_iterator<int>( out, " " ) );
    out<<'\n';
    return (EXIT_SUCCESS);
}