Cod sursa(job #2397049)

Utilizator AlexNeaguAlexandru AlexNeagu Data 4 aprilie 2019 09:39:39
Problema Algoritmul lui Dijkstra Scor 80
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.91 kb
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

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

const int NMAX=50005;
const int HeapMax=500005;
const int oo=2000000000;
vector < pair < int, int > > T[NMAX];
int Distante[NMAX],Heap[HeapMax],L;
bool Viz[NMAX];
int N,M;

inline void swap(int a, int b)
{
    int aux=Heap[a];
    Heap[a]=Heap[b];
    Heap[b]=aux;
}
void upheap(int x)
{
    int tata=x/2;
    if (tata!=0&&Heap[x]<Heap[tata])
    {
        swap(x,tata);
        upheap(tata);
    }
}
void downheap(int x)
{
    int fiu;
    int fiu_st=x*2;
    int fiu_dr=x*2+1;
    if (fiu_dr<=L&&Heap[fiu_dr]<Heap[fiu_st])
        fiu=fiu_dr;
    else fiu=fiu_st;
    if (fiu<=L && Heap[fiu]<Heap[x])
    {
        swap(fiu,x);
        downheap(fiu);
    }

}
void heap_insert(int x)
{
    L++;
    Heap[L]=x;
    upheap(L);
}
void pop()
{
    swap(1,L);
    --L;
    if (L>0)
        downheap(1);
}
int main()
{
    fin>>N>>M;
    for (int i=1; i<=M; i++)
    {
        int x,y,cost;
        fin>>x>>y>>cost;
        T[x].push_back(make_pair(y,cost));
    }
  for (int i=1; i<=N; i++)
    Distante[i]=oo;
    Distante[1]=0;
    heap_insert(1);
    Viz[1]=true;

    while (L>0)
    {
        int Nod=Heap[1];
        pop();
        Viz[Nod]=false;
        for (unsigned int i=0; i<T[Nod].size(); i++)
        {
            int Vecin=T[Nod][i].first;
            int Cost=T[Nod][i].second;
            if (Distante[Nod]+Cost<Distante[Vecin])
            {
                Distante[Vecin]=Distante[Nod]+Cost;
                if (!Viz[Vecin])
                {
                    heap_insert(Vecin);
                    Viz[Vecin]=true;
                }
            }
        }
    }

    for (int i=2; i<=N; i++)
        if (Distante[i]==oo)
        fout<<"0 ";
    else fout<<Distante[i]<<" ";
    return 0;
}