Cod sursa(job #1366890)

Utilizator somuBanil Ardej somu Data 1 martie 2015 14:29:39
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.46 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define inf 1<<30
#define nmax 50005

using namespace std;

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

int n, m;
int cost[nmax], used[nmax];
vector < pair <int, int> > G[nmax];
queue < pair<int, int> > q;

void bellmanFord(int nod) {
    cost[nod] = 0;
    q.push(make_pair(nod, cost[nod]));
    for (; q.size();) {
        int nodCurent = q.front().first;
        int costCurent = q.front().second;
        q.pop();
        for (int i = 0; i < G[nodCurent].size(); i++) {
            int vecinCurent = G[nodCurent][i].first;
            int costVecin = G[nodCurent][i].second;
            
            if (cost[vecinCurent] > costCurent + costVecin) {
                cost[vecinCurent] = costCurent + costVecin;
                q.push(make_pair(vecinCurent, cost[vecinCurent]));
                if (used[vecinCurent] > n) {
                    fout << "Ciclu negativ!\n";
                    return;
                }
                used[vecinCurent]++;
            }
            
        }
    }
    for (int i = 2; i <= n; i++)
        fout << cost[i] << " ";
    fout << "\n";
}

int main() {
    
    fin >> n >> m;
    for (int i = 1; i <= m; i++) {
        int x, y, z;
        fin >> x >> y >> z;
        G[x].push_back(make_pair(y, z));
    }
    
    for (int i = 1; i <= n; i++)
        cost[i] = inf;
    
    bellmanFord(1);
    
    fin.close();
    fout.close();
    
    return 0;
}