Cod sursa(job #1118278)

Utilizator eugen_ptrEugen Patru eugen_ptr Data 24 februarie 2014 09:36:44
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.56 kb
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>

#define Nmax 50005
#define INF 0x3f3f3f3f

using namespace std;

vector < pair <int, int> > L[Nmax];
queue <int> Q;
int d[Nmax], viz[Nmax], nr[Nmax];
int n, m;

void citire()
{
    scanf("%d %d",&n, &m);
    for (int i=1; i<=m; i++)
    {
        int x, y, c;
        scanf("%d %d %d",&x, &y, &c);
        L[x].push_back(make_pair(c, y));
    }
}

void initializare()
{
    for (int i=2; i<=n; i++)
        d[i] = INF;
}

int bellmanFord()
{
    Q.push(1);
    viz[1] = 1;
    nr[1] = 1;
    while(!Q.empty())
    {
        int x = Q.front();
        Q.pop();
        viz[x] = 0;
        for (int i=0; i<L[x].size(); i++)
        {
            int cost = L[x][i].first;
            int vecin = L[x][i].second;
            if (d[vecin] > d[x] + cost)
            {
                d[vecin] = d[x] + cost;
                if (viz[vecin] == 0)
                {
                    viz[vecin] = 1;
                    Q.push(vecin);
                }
                nr[vecin] ++;
                if(nr[vecin] > n)
                    return 1;

            }
        }
    }
    return 0;
}

void afisare()
{
    for (int i=2; i<=n; i++)
        printf("%d ",d[i]);
}

int main()
{
    freopen("bellmanford.in","r",stdin);
    freopen("bellmanford.out","w",stdout);
    citire();
    initializare();
    if (bellmanFord())
        printf("Ciclu negativ!");
    else
        afisare();
    return 0;
}