Cod sursa(job #2806834)

Utilizator AndreeaGeamanuAndreea AndreeaGeamanu Data 23 noiembrie 2021 01:16:04
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.59 kb
#include <iostream>
#include <fstream>
#include <bits/stdc++.h>

#define nmax 50010
const int inf = 0x3f3f3f3f;

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

vector <pair<int,int>> la[nmax];
int d[nmax], frecv[nmax]={0};
queue <int> q;
bool inq[nmax];
int cn=0;


int main()
{   int n,m,x,y,c;
    f>>n>>m;

    // Se introduc perechile (nod, cost) in liste de adiacenta
    for(int i=1; i<=m; i++){
        f>>x>>y>>c;
        la[x].push_back(make_pair(y,c));
    }

    // Se seteaza vectorul de distante minime cu inf
    memset(d, inf, sizeof(d));
    d[1]=0;

    // Se adauga nodul de start in coada
    q.push(1);

    while(!q.empty() && cn==0){
        int nod = q.front();
        q.pop();
        inq[nod]=false;
        // Pentru fiecare vecin al nodului curent se actualizeaza distanta minima
        for(int k=0; k<la[nod].size(); k++){
            int nod2 = la[nod][k].first;
            int cost = la[nod][k].second;
            if(d[nod]+cost< d[nod2]){
                d[nod2] = d[nod]+cost;
                if(!inq[nod2]){
                    if(frecv[nod2]>n) cn=1;
                    else {
                        inq[nod2]=true;
                        q.push(nod2);
                        frecv[nod2]++;
                    }
                }
            }
        }
    }

    // Afisare
    if(cn==1) g<<"Ciclu negativ!";
    else
        for(int l=2; l<=n; l++){
            if(d[l]==inf) g<<0<<" ";
            else g<<d[l]<<" ";
        }

    f.close();
    g.close();
    return 0;
}