Cod sursa(job #2505640)

Utilizator iarinatudorTudor Iarina Maria iarinatudor Data 7 decembrie 2019 10:00:48
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.38 kb
#include <iostream>
#include <fstream>
#include <climits>
#include <vector>
#include <queue>

using namespace std;

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

int n,m;
vector <pair <int,int> > G[50005];
queue <int> Q;
int dp[50005], ok[50005], cnt[50005]; ///dp pt drum minim de la 1 la orice nod,ok daca avem sau nu nodul in coada si cnt ca sa vedem la ce pas suntem
void citire()
{
    fin>>n>>m;
    for(int i=1; i<=m; i++)
    {
        int x,y,c;
        fin>>x>>y>>c;
        G[x].push_back({y,c});
    }
    for(int i=2; i<=n; i++)
        dp[i]=INT_MAX/2;
    Q.push(1);
    ok[1]=1;
    cnt[1]++;
}
bool neg;
void bellmanford()
{
    while(!Q.empty()&&!neg)
    {
        int x=Q.front();
        Q.pop();
        ok[x]=0;
        for(auto &v: G[x])
        {
            int y=v.first;
            int c=v.second;
            if(dp[y]>dp[x]+c)
            {
                dp[y]=dp[x]+c;
                if(!ok[y])
                {
                    ok[y]=1;
                    Q.push(y);
                    cnt[y]++;
                    if(cnt[y]>n)
                        neg=1;
                }
            }
        }
    }
}
int main()
{
    citire();
    bellmanford();
    if(!neg)
        for(int i=2; i<=n; i++)
            fout<<dp[i]<<" ";
    else fout<<"Ciclu negativ!";
    return 0;
}