Cod sursa(job #3124420)

Utilizator RoxiGeorgianaAlbastroiu Roxana Georgiana RoxiGeorgiana Data 28 aprilie 2023 17:17:35
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.45 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

const int nmax = 50003, oo = 1000000;
int n, m, d[nmax], frecv[nmax];
bool isInQ[nmax];
vector < pair < int, int > > v[nmax];
queue < int > q;

void read() 
{
    fin >> n >> m;
    while (m--) 
    {
        int x, y, z;
        fin >> x >> y >> z;
        v[x].push_back(make_pair(y, z));
    }
}


int bellmanFord(int start) 
{
    int nod;
    for (int i = 1; i <= n; i++) 
    {
        d[i] = oo;
        isInQ[i] = false;
    }

    d[start] = 0;
    isInQ[start] = true;
    q.push(start);

    while (!q.empty()) 
    {
        nod = q.front();
        q.pop();
        isInQ[nod] = false;

        if (++frecv[nod] > n)
            return 0;

        for (int i = 0; i < v[nod].size(); i++) 
        {
            int vecin = v[nod][i].first;
            int cost = v[nod][i].second;
            if (d[nod] + cost < d[vecin]) 
            {
                d[vecin] = d[nod] + cost;
                if (!isInQ[vecin]) 
                {
                    isInQ[vecin] = true;
                    q.push(vecin);
                }
            }
        }
    }
    return 1;
}

int main() 
{
    read();
    if (!bellmanFord(1))
        fout << "Ciclu negativ!";
    else for (int i = 2; i <= n; i++)
        fout << d[i] << " ";
}