Cod sursa(job #2368148)

Utilizator UnseenMarksmanDavid Catalin UnseenMarksman Data 5 martie 2019 14:15:58
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.69 kb
#include <bits/stdc++.h>
using namespace std;

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

const int maxn = 50005;
const int maxm = 250005;
const int inf = 2000000000;
int n, m, last;
int d[maxn];
bool ok[maxn];

struct muchie{
    long a, b, c;
} e[maxm];

vector<int>A[maxn];
struct str{
    int nod;
    bool operator <(const str &other)const
    {
        return d[nod]>d[other.nod];
    }
};
priority_queue<str>H;

void BellmanFord()
{
    int nod, poz;
    long long pas=0;

    while(!H.empty() && pas<=1LL*n*m)
    {
        pas++;
        //pop_heap(Heap.begin(),Heap.end());
        //per=Heap.back();
       // Heap.pop_back();
        nod=H.top().nod;
        H.pop();
        ok[nod]=0;
        for(auto it:A[nod])
        {
            if(d[e[it].a] + e[it].c < d[e[it].b])
            {
                d[e[it].b] = d[e[it].a] + e[it].c;
                if(!ok[e[it].b])
                {
                    ok[e[it].b]=1;
                    //Heap.push_back({-d[e[poz].b], e[poz].b});
                    H.push({e[it].b});
                    //push_heap(Heap.begin(),Heap.end());
                }
            }
        }
    }
}

int main()
{
    long a,b,c;

    fin>>n>>m;
    for(long i=1; i<=m; i++)
    {
        fin>>e[i].a>>e[i].b>>e[i].c;
        A[e[i].a].push_back(i);
    }

    for(long i=2; i<=n; i++)
        d[i]=inf;

    H.push({1});
    BellmanFord();
    for(int i=1; i<=m; i++)
    {
        if(d[e[i].a] + e[i].c < d[e[i].b])
        {
            fout<<"Ciclu negativ!\n";
            return 0;
        }
    }
    for(int i=2; i<=n; i++)
        fout<<d[i]<<' ';

    return 0;
}