Cod sursa(job #2764941)

Utilizator SabailaCalinSabaila Calin SabailaCalin Data 23 iulie 2021 19:07:00
Problema Algoritmul Bellman-Ford Scor 10
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.9 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

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

int n, m, cntVisited[MAX], dist[MAX];
bool inQueue[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] = POSITIVE_INFINITY;
    }
    dist[1] = 0;

    for (int k = 1; k < m; k++)
    {
        for (int i = 1; i <= n; i++)
        {
            for (int j = 0; j < V[i].size(); j++)
            {
                int neighbour = V[i][j].first;
                int cost = V[i][j].second;
                if (dist[i] + cost < dist[neighbour])
                {
                    dist[neighbour] = dist[i] + cost;
                }
            }
        }
    }

    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j < V[i].size(); j++)
        {
            int neighbour = V[i][j].first;
            int cost = V[i][j].second;
            if (dist[i] + cost < dist[neighbour] || dist[i] == NEGATIVE_INFINITY)
            {
                dist[neighbour] = NEGATIVE_INFINITY;
                return false;
            }
        }
    }

    return true;
}

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

//10 13
//
//1 2 5
//2 7 60
//2 6 30
//2 4 20
//4 3 10
//4 5 75
//3 4 -15
//5 10 100
//6 9 50
//6 7 5
//6 5 25
//7 8 -50
//8 9 -10