Cod sursa(job #2982329)

Utilizator SabailaCalinSabaila Calin SabailaCalin Data 19 februarie 2023 22:38:04
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.64 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

const int SIZE = 50005;
const int INF = 0x3f3f3f3f;

int n, m;

vector < pair <int, int> > adj[SIZE];

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

void SPFA(int startNode)
{
    queue <int> q;
    vector <int> dist(SIZE, INF);
    vector <int> len(SIZE, 0);
    vector <bool> inQueue(SIZE, false);

    q.push(startNode);
    inQueue[startNode] = true;
    dist[startNode] = 0;

    while (q.empty() == false)
    {
        int node = q.front();
        inQueue[node] = false;
        q.pop();

        for (unsigned int i = 0; i < adj[node].size(); i++)
        {
            int neighbour = adj[node][i].first;
            int cost = adj[node][i].second;

            if (dist[node] + cost < dist[neighbour])
            {
                dist[neighbour] = dist[node] + cost;
                len[neighbour] = len[node] + 1;

                if (len[neighbour] >= n)
                {
                    g << "Ciclu negativ!";
                    return;
                }

                if (inQueue[neighbour] == false)
                {
                    q.push(neighbour);
                    inQueue[neighbour] = true;
                }
            }
        }
    }

    for (int i = 2; i <= n; i++)
    {
        g << dist[i] << " ";
    }
}

int main()
{
    Read();
    SPFA(1);

    return 0;
}