Cod sursa(job #2764875)

Utilizator SabailaCalinSabaila Calin SabailaCalin Data 23 iulie 2021 00:13:27
Problema Algoritmul Bellman-Ford Scor 35
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.66 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

const int INFINITY = (1 << 31) - 1;
const int MAX = 50001;

int n, m;
int dist[MAX], cntInQueue[MAX];
bool onQueue[MAX];
vector <pair <int, int>> V[MAX];
queue <int> Q;

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

bool BellmanFord(int startNode)
{
    for (int i = 1; i <= n; i++)
    {
        dist[i] = INFINITY;
    }

    dist[startNode] = 0;
    Q.push(startNode);
    onQueue[startNode] = true;
    cntInQueue[startNode]++;

    while (Q.empty() == false)
    {
        int node = Q.front();
        Q.pop();
        onQueue[node] = false;

        if (cntInQueue[node] >= n)
        {
            return false;
        }

        for (int i = 0; i < V[node].size(); i++)
        {
            int neighbour = V[node][i].first;
            int cost = V[node][i].second;
            if (dist[node] + cost < dist[neighbour])
            {
                dist[neighbour] = dist[node] + cost;
                if (onQueue[neighbour] == false)
                {
                    Q.push(neighbour);
                    onQueue[neighbour] = true;
                }
            }
        }
    }
    return true;
}

int main()
{
    Read();
    if (BellmanFord(1) == false)
    {
        g << "Ciclu negativ!";
    }
    else
    {
        for (int i = 2; i <= n; i++)
        {
            g << dist[i] << " ";
        }
    }
}