Cod sursa(job #2777902)

Utilizator rares89_Dumitriu Rares rares89_ Data 25 septembrie 2021 20:55:37
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.25 kb
#include <fstream>
#include <vector>
#include <queue>
#define INF 0x3f3f3f3f
#define PA pair<int, int>

using namespace std;

ifstream fin("bellmanford.in");
ofstream fout("bellmanford.out");

int n, m, x, y, z, c[50005], v[50005];
vector<PA> G[50005];

bool bellmanford(int s) {
    for(int i = 1; i <= n; i++) {
        c[i] = INF;
    }
    c[s] = 0;
    queue<int> Q;
    Q.push(s);
    while(!Q.empty()) {
        int nod = Q.front();
        v[nod]++;
        // se ver daca s-a gasit un ciclu negativ
        if(v[nod] >= n) {
            return false;
        }
        Q.pop();
        for(unsigned int i = 0; i < G[nod].size(); i++) {
            int vecin = G[nod][i].first;
            int cost = G[nod][i].second;
            if(c[vecin] > c[nod] + cost) {
                c[vecin] = c[nod] + cost;
                Q.push(vecin);
            }
        }
    }
    return true;
}

int main() {
    fin >> n >> m;
    for(int i = 1; i <= m; i++) {
    	fin >> x >> y >> z;
        G[x].push_back({y, z});
    }
    fin.close();
    if(bellmanford(1)) {
        for(int i = 2; i <= n; i++) {
            fout << c[i] << " ";
        }
    } else {
        fout << "Ciclu negativ!";
    }
    fout.close();
	return 0;
}