Cod sursa(job #2619735)

Utilizator proflaurianPanaete Adrian proflaurian Data 28 mai 2020 13:00:36
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.33 kb
#include <fstream>
#include <vector>
#include <queue>
#include <bitset>
#include <tuple> /// pentru tie

using namespace std;
ifstream f("bellmanford.in");
ofstream g("bellmanford.out");
const int N = 50001;
const int oo = 1000000000; /// sau cat deduc din enunt
int n,m,d[N],cnt[N];
vector<pair<int,int>> v[N];
queue<int> q;
bitset<N> used;
int main()
{
    f>>n>>m;
    for(;m;m--)
    {
        int x,y,dist;
        f>>x>>y>>dist;
        v[x].push_back(make_pair(y,dist));
    }
    for(int i=1;i<=n;i++)
        d[i]=oo;
    int s=1; /// sau se citeste anterior
    d[s]=0;
    q.push(s);
    used[s]=1;
    while(q.size())
    {
        int nod = q.front();
        q.pop();
        used[nod]=0;
        for(auto it:v[nod])
        {
            int vec,distEdge;
            tie(vec,distEdge)=it;
            if(d[vec]>d[nod]+distEdge)
            {
                d[vec]=d[nod]+distEdge;
                cnt[vec]++;
                if(cnt[vec]>n)
                {
                    g<<"Ciclu negativ!";
                    return 0;
                }

                if(!used[vec])
                {
                    q.push(vec);
                    used[vec]=1;
                }
            }
        }

    }
    for(int i = 2 ; i <= n; i++)
        g<<d[i]<<' ';
    return 0;
}