Cod sursa(job #873936)

Utilizator vendettaSalajan Razvan vendetta Data 7 februarie 2013 19:20:35
Problema Algoritmul Bellman-Ford Scor 35
Compilator cpp Status done
Runda Arhiva educationala Marime 1.59 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <set>
#include <queue>
#include <deque>

using namespace std;

ifstream f("bellmanford.in");
ofstream g("bellmanford.out");

#define nmax 50005
#define inf (1<<30)
#define ll long long

int n, m, dist[nmax], q[nmax], viz[nmax];
bool inCoada[nmax];
vector< pair<int,int> > gf[nmax];

void citeste(){
    f >> n >> m;
    int x, y, z;
    for(int i=1; i<=m; ++i){
        f >> x >> y >> z;
        gf[x].push_back( make_pair(y, z) );
    }
}

void rezolva(){
    q[0] = 1;
    int st = 1; int dr = 1;
    q[dr] = 1; inCoada[1] = 1;
    for(int i=2; i<=n; ++i) dist[i] = inf;
    for(; st<=dr; ){
        int nod = q[st]; ++st;
        inCoada[nod] = 0;// eu il scot acum deci sa stiu ca l-am scos; daca ii mai minimizez distanta sa il bag in coada pt ca il scot acum
        for(int i=0; i<gf[nod].size(); ++i){
            int vc = gf[nod][i].first;
            int cost = gf[nod][i].second;
            if ( dist[vc] > dist[nod] + cost){
                dist[vc] = dist[nod] + cost;
                if (inCoada[vc] == 0){//doar daca nu a mai fost bagat in coada
                    if (viz[vc] > n){// am ciclu
                        g << "Ciclu negativ!\n";
                        return;
                    }
                    ++viz[vc];
                    inCoada[vc] = 1;
                    q[++dr] = vc;
                }
            }
        }
    }
    for(int i=2; i<=n; ++i) g << dist[i] << " ";
}

int main(){
    citeste();
    rezolva();

    f.close();
    g.close();

    return 0;
}