Cod sursa(job #604355)

Utilizator a_h1926Heidelbacher Andrei a_h1926 Data 21 iulie 2011 22:15:00
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 2.3 kb
#include <iostream>
#include <vector>

#define NMax 50005
#define Inf 2000000000
#define v first
#define c second

using namespace std;

vector < pair <int, int> > G[NMax];
int N, NHeap, Heap[NMax], Poz[NMax], D[NMax];

void Read ()
{
    freopen ("dijkstra.in", "r", stdin);
    int M;
    scanf ("%d %d", &N, &M);
    for (; M>0; --M)
    {
        int X, Y, Z;
        scanf ("%d %d %d", &X, &Y, &Z);
        G[X].push_back (make_pair (Y, Z));
    }
}

void Print ()
{
    freopen ("dijkstra.out", "w", stdout);
    for (int i=2; i<=N; ++i)
    {
        if (D[i]==Inf)
        {
            D[i]=0;
        }
        printf ("%d ", D[i]);
    }
    printf ("\n");
}

inline void Swap (int X, int Y)
{
    int Aux;
    Aux=Poz[Heap[X]];
    Poz[Heap[X]]=Poz[Heap[Y]];
    Poz[Heap[Y]]=Aux;
    Aux=Heap[X];
    Heap[X]=Heap[Y];
    Heap[Y]=Aux;
}

void Percolate (int X)
{
    int Father=(X>>1);
    while (Father>0)
    {
        if (D[Heap[X]]<D[Heap[Father]])
        {
            Swap (X, Father);
            X=Father;
            Father=(X>>1);
        }
        else
        {
            return;
        }
    }
}

void Sift (int X)
{
    int Son=(X<<1);
    while (Son<=NHeap)
    {
        if (Son+1<=NHeap and D[Heap[Son+1]]<D[Heap[Son]])
        {
            ++Son;
        }
        if (D[Heap[Son]]<D[Heap[X]])
        {
            Swap (X, Son);
            X=Son;
            Son=(X<<1);
        }
        else
        {
            return;
        }
    }
}

void Delete (int X)
{
    Swap (X, NHeap);
    Poz[Heap[NHeap]]=0;
    Heap[NHeap]=0;
    --NHeap;
    Sift (X);
}

void Initialize (int Start)
{
    NHeap=N;
    for (int i=1; i<=N; ++i)
    {
        D[i]=Inf;
        Heap[i]=Poz[i]=i;
    }
    D[Start]=0;
    Swap (1, Start);
}

void Dijkstra (int Start)
{
    Initialize (Start);
    while (NHeap>0)
    {
        int X=Heap[1];
        Delete (1);
        for (unsigned i=0; i<G[X].size (); ++i)
        {
            int V=G[X][i].v;
            int C=G[X][i].c;
            if (D[X]+C<D[V])
            {
                D[V]=D[X]+C;
                Percolate (Poz[V]);
            }
        }
    }
}

int main()
{
    Read ();
    Dijkstra (1);
    Print ();
    return 0;
}