Cod sursa(job #1818122)

Utilizator geo_furduifurdui geo geo_furdui Data 28 noiembrie 2016 20:41:58
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.65 kb
#include <fstream>
#include<climits>
using namespace std;
ifstream cin ("dijkstra.in");
ofstream cout ("dijkstra.out");
int d[50010],t[3][250010],start[50010],heap[50010],npoz[50010],m,n;
void read ()
{ int x,y,c,k=0;
    cin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        cin>>x>>y>>c;
        t[0][++k]=y; t[1][k]=start[x]; t[2][k]=c; start[x]=k;
    }
}
void climb (int poz)
{
    int val=heap[poz];
    while(3>2)
    {
        if(poz>1 && d[heap[poz/2]]>d[val])
            heap[poz]=heap[poz/2],npoz[heap[poz]]=poz,poz/=2;
        else { heap[poz]=val; npoz[heap[poz]]=poz; break; }
    }
}
void down (int poz)
{
    int val=heap[poz],fiu;
    while(3>2)
    {
        fiu=0;
        if(poz*2<=m) fiu=poz*2;
        if(poz*2+1<=m && d[heap[fiu]]>d[heap[fiu+1]]) fiu=poz*2+1;
        if(fiu!=0 && d[heap[fiu]]<d[val])
            heap[poz]=heap[fiu],npoz[heap[poz]]=poz,poz=fiu;
        else { heap[poz]=val; npoz[heap[poz]]=poz; break; }
    }
}
void init ()
{
    for(int i=2;i<=n;i++) d[i]=INT_MAX;
}
void dijkstra ()
{ heap[1]=1; m=1;
    for(int i=1;i<=n;i++)
    {
        int poz=heap[1]; npoz[heap[1]]=0;  heap[1]=heap[m]; npoz[heap[1]]=1; m--; down(1);
        int x=start[poz];
        while(x)
        {
            if(d[t[0][x]]>d[poz]+t[2][x])
            {
                d[t[0][x]]=d[poz]+t[2][x]; if(npoz[t[0][x]]!=0) climb(npoz[t[0][x]]); else { heap[++m]=t[0][x]; climb(m); }
            } x=t[1][x];
        }
    }
}
void write ()
{
    for(int i=2;i<=n;i++)
    { if(d[i]==INT_MAX) d[i]=0;  cout<<d[i]<<" ";}
}
int main()
{
    read();
    init();
    dijkstra();
    write();
    return 0;
}