Cod sursa(job #2837468)

Utilizator puica2018Puica Andrei puica2018 Data 22 ianuarie 2022 10:52:16
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.69 kb
#include <bits/stdc++.h>
#define oo 2000000001
using namespace std;

/**
*/
ifstream fin("bellmanford.in");
ofstream fout("bellmanford.out");
       ///   nod, cost
vector< pair<int, int> > L[50002];
int viz[50002]; /// viz[i]=1 daca nodul i este pus in coada
int n, d[50002]; /// d[i] = costul minim pana la nodul i
int contor[50002]; /// numar de cate ori am pus nodul i
                   /// in coada
queue<int> q;

void Citire()
{
    int i, x, y, c, m;
    fin >> n >> m;
    for (i = 1; i <= m; i++)
    {
        fin >> x >> y >> c;
        L[x].push_back({y, c});
    }
}

void BellmanFord()
{
    bool existaNegative;
    int i, x, c;
    /// initializari:
    for (i = 2; i <= n; i++)
        d[i] = oo;
    existaNegative = false;
    viz[1] = 1;
    q.push(1);
    contor[1] = 1;
    while (!q.empty() && !existaNegative)
    {
        x = q.front();
        q.pop();
        viz[x] = 0;
        for (auto w : L[x])
        {
            i = w.first;
            c = w.second;
            if (d[i] > d[x] + c)
            {
                d[i] = d[x] + c;
                if (viz[i] == 0)
                {
                    if (contor[i] > n) existaNegative = true;
                    else
                    {
                        q.push(i);
                        viz[i] = 1;
                        contor[i]++;
                    }
                }
            }
        }
    }
    if (existaNegative) fout << "Ciclu negativ!\n";
    else
    {
        for (i = 2; i <= n; i++)
            fout << d[i] << " ";
        fout << "\n";
    }
}

int main()
{
    Citire();
    BellmanFord();
    fout.close();
    return 0;
}