Cod sursa(job #855807)

Utilizator R.A.RFMI Romila Remus Arthur R.A.R Data 15 ianuarie 2013 17:20:28
Problema Algoritmul lui Dijkstra Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 1.56 kb
#include <fstream>
#include <vector>
#define LS (p<<1)
#define RS ((p<<1)+1)
#define Ft (p>>1)
#define  INF (1<<30)
#define NMAX 50004

using namespace std;

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

int N,M,D[NMAX],Dist[NMAX];

vector<pair<int,int> > V[NMAX];

int Heap[NMAX<<1],Size;

void Down_Heap(int p)
{
    int min = p,aux;
    if( D[Heap[LS]] < D[Heap[min]])
        min = LS;
    if( D[Heap[RS]] < D[Heap[min]])
        min = RS;
    if(p != min)
        aux = Heap[min],Heap[min] = Heap[p],Heap[p] = aux;
}

void Up_Heap(int p)
{
    if(p&&D[Heap[p]] < D[Heap[Ft]])
    {
        int aux = Heap[p];
        Heap[p] = Heap[Ft];
        Heap[Ft] = aux;
        Up_Heap(Ft);
    }
}

void Push_Heap(int nod)
{
    Heap[++Size] = nod;
    Up_Heap(Size);
}

void Pop_Heap()
{
    Heap[1] = Heap[Size--];
    Down_Heap(1);
}


int main ()
{
    int i,x,y,c;
    in>>N>>M;
    while(M--)
    {
        in>>x>>y>>c;
        V[x].push_back(make_pair(y,c));
    }
    for(D[0] = -1,i=2;i<=N;i++)
        D[i] = Dist[i] = INF;
    for(i = N;i;i--)
    {
        if(i>N/2)
            Heap[++Size] = i;
        else
        Push_Heap(i);
    }
    while(Size)
    {
        x = Heap[1];
        Pop_Heap();
        for(i=0;i<V[x].size();i++)
        {
            y = V[x][i].first;
            c = V[x][i].second;
            if(Dist[y] > Dist[x]+c)
                D[y] = Dist[y] = Dist[x]+c,Push_Heap(y);
        }
    }
    for(i=2;i<=N;i++)
        out<<(Dist[i]!= INF ? Dist[i] : 0)<<' ';
}