Cod sursa(job #3265680)

Utilizator stefan0211Tacu Darius Stefan stefan0211 Data 2 ianuarie 2025 14:27:55
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.23 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <climits>
#include <algorithm>
using namespace std;

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

struct ComparePairs
{
    bool operator()(const pair<int, int> &p1, const pair<int, int> &p2)
    {
        return p1.second > p2.second;
    }
};

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

void BellmanFord(vector<vector<pair<int, int>>> &adj_matrix, vector<int> &distanta, int n)
{
    queue<int> q;
    vector<bool> in_q(n + 1);
    vector<int> cnt_in_q(n + 1, 0);
    q.push(1);
    distanta[1] = 0;
    in_q[1] = true;
    while (!q.empty())
    {
        int nod_curent = q.front();
        q.pop();

        in_q[nod_curent] = false;
        for (auto &vecin : adj_matrix[nod_curent])
        {
            int nod_vecin = vecin.first;
            int cost = vecin.second;
            if (distanta[nod_curent] < INT_MAX && distanta[nod_curent] + cost < distanta[nod_vecin])
            {
                distanta[nod_vecin] = distanta[nod_curent] + cost;
                if (!in_q[nod_vecin])
                {

                    if (cnt_in_q[nod_vecin] > n)
                    {
                        g << "Ciclu negativ!";
                        exit(0);
                    }
                    q.push(nod_vecin);
                    in_q[nod_vecin] = true;
                    cnt_in_q[nod_vecin]++;
                }
            }
        }
    }

    for (int nod_curent = 1; nod_curent <= n; nod_curent++)
    {
        for (auto &vecin : adj_matrix[nod_curent])
        {
            int nod_vecin = vecin.first;
            int cost = vecin.second;
            if (distanta[nod_curent] + cost < distanta[nod_vecin])
            {

                g << "Ciclu negativ!";
                exit(0);
            }
        }
    }
}

int main()
{
    int n, m;
    f >> n >> m;

    vector<vector<pair<int, int>>> adj(n + 1);

    Read(adj, m);

    vector<int> distanta(n + 1, INT_MAX);

    BellmanFord(adj, distanta, n);

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

    return 0;
}