Cod sursa(job #2670127)

Utilizator Giulian617Buzatu Giulian Giulian617 Data 9 noiembrie 2020 09:03:30
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.29 kb
#include<bits/stdc++.h>
using namespace std;
ifstream f("bellmanford.in");
ofstream g("bellmanford.out");
const int NMAX=50005,INF=0x3F3F3F3F;
int n,m,x,y,c;
vector<vector<pair<int,int>>>v;
vector<int>a;
bool spfa(int start,vector<int>& d)
{
    d.assign(n+1,INF);
    vector<int>cnt(n+1,0);
    queue<int>q;
    bitset<NMAX>inqueue;
    d[start]=0;
    q.push(start);
    inqueue[start]=1;
    while(!q.empty())
    {
        int now=q.front();
        q.pop();
        inqueue[now]=0;
        for(auto edge : v[now])
        {
            int to=edge.first,len=edge.second;///destinatia+costul
            if(d[now]+len<d[to])
            {
                d[to]=d[now]+len;
                if(!inqueue[to])
                {
                    q.push(to);
                    inqueue[to]=1;
                    cnt[to]++;
                    if(cnt[to]>=n)
                        return 0;///ciclu negativ
                }
            }
        }
    }
    return 1;
}
int main()
{
    f>>n>>m;
    v.resize(n+5);
    for(int i=1; i<=m; i++)
    {
        f>>x>>y>>c;
        v[x].emplace_back(y,c);
    }
    bool ans=spfa(1,a);
    if(ans==0)
        g<<"Ciclu negativ!";
    else
        for(int i=2; i<=n; i++)
            g<<a[i]<<" ";
    return 0;
}