Mai intai trebuie sa te autentifici.
Cod sursa(job #1906631)
Utilizator | Data | 6 martie 2017 15:29:14 | |
---|---|---|---|
Problema | Algoritmul lui Dijkstra | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 2.32 kb |
#include <fstream>
using namespace std;
ifstream f("dijkstra.in");
ofstream g("dijkstra.out");
#define inf 2000000000
struct nod
{
int where,cost;
nod *urm;
};
typedef nod *pnod;
pnod v[50003],p;
void ad(int x,int y,int cost)
{
p=new nod;
p->where=y;
p->cost=cost;
p->urm=v[x]->urm;
v[x]->urm=p;
}
int n,m;
int dist[50003],poz[50003],h[50003];
void upheap(int what)
{
int tata;
while ( what > 1 )
{
tata = what >> 1;
if ( dist[ poz[tata] ] > dist[ poz[what] ] )
{
swap(h[poz[tata]],h[poz[what]]);
swap(poz[tata],poz[what]);
what = tata;
}
else
what = 1;
}
}
int k;
void downheap(int fi)
{
int now;
do
{
now=0;
if(fi*2<=k)
{
now=fi*2;
if(now+1<=k and dist[poz[now+1]]<dist[poz[now]])
now+=1;
if(dist[poz[fi]]>dist[poz[now]])
{
swap(h[poz[fi]],h[poz[now]]);
swap(poz[now],poz[fi]);
fi=now;
}
else
now=0;
}
}while(now);
}
int main()
{
int i,x,y,c;
f>>n>>m;
for(i=1;i<=n;i++)
{
v[i]=new nod;
v[i]->urm=0;
dist[i]=inf;
h[i]=-1;
}
for(i=1;i<=m;i++)
{
f>>x>>y>>c;
ad(x,y,c);
}
p=v[1]->urm;
dist[1]=0;
h[1]=1;
k=1;
int minim;
poz[1]=1;
while(k)
{
minim=poz[1];
swap(poz[1],poz[k]);
h[poz[1]]=1;
k--;
downheap(1);
p=v[minim]->urm;
while(p)
{
if(dist[p->where]>dist[minim]+p->cost)
{
dist[p->where]=dist[minim]+p->cost;
if(h[p->where]==-1)
{
k+=1;
poz[k]=p->where;
h[p->where]=k;
upheap(k);
}
else
{
upheap(h[p->where]);
}
}
p=p->urm;
}
}
for(i=2;i<=n;i++)
if(dist[i]==inf)
g<<"0 ";
else
g<<dist[i]<<" ";
g<<'\n';
return 0;
}