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Cod sursa(job #911760)
#include <fstream>
#include <vector>
#define Infinit 1000000
using namespace std;
ifstream fin("dijkstra.in");
ofstream fout("dijkstra.out");
struct Arc{int vf,c;
Arc(int nod, int cost) { vf = nod; c = cost; }
};
int n,m,x0,start;
vector<Arc> G[50000];
//Arc G[10000][10001];
int poz[10001]; //poz[i]=-1 daca vf i nu a fost pus in heap, respectiv 1 daca a fost pus in heap
int dmin[10001]; //distantele minime
int prec[10001]; //pot reconstitui drumul
int h[10001],lgh; //in h sunt varfurile organizate ca min-heap
int M[10001]; //multimea varfurilor selectate
void citire();
int extrage();
void adauga_arc(int x, int y, int cost);
void dijkstra();
void InsertHeap(int vf);
void upGrade(int fiu);
void afisare();
int main()
{
citire();
dijkstra();
afisare();
fout.close();
return 0;
}
void citire()
{
int i,x,y,cost;
fin>>n>>m;
x0=1;
for(i=0;i<m;i++)
{
fin>>x>>y>>cost;
G[x].push_back(Arc(y,cost));
//adauga_arc(x,y,cost);
}
}
void adauga_arc(int x,int y,int cost)
{
G[x][0].c++;
G[x][G[x][0].c].c=cost;
G[x][G[x][0].c].vf=y;
}
void dijkstra()
{
int i,vfmin,nrs=0,j;
//initializari
for(i=1;i<=n;i++) {dmin[i]=Infinit; prec[i]=x0; poz[i]=-1;}
//x0 intra in heap pe poz 1
dmin[x0]=0; prec[x0]=-1; poz[x0]=1; h[1]=x0; lgh=1;
while(nrs<n)
{
vfmin=extrage();
M[vfmin]=1; nrs++;
//parcurg lista de adiacenta a lui vfmin
for(j=0;j<G[vfmin].size();j++) //G[vfmin][0].c;j++)
if(!M[G[vfmin][j].vf]) //nu a fost deja selectat
if(dmin[G[vfmin][j].vf]>dmin[vfmin]+G[vfmin][j].c)
{
dmin[G[vfmin][j].vf]=dmin[vfmin]+G[vfmin][j].c;
prec[G[vfmin][j].vf]=vfmin;
if(poz[G[vfmin][j].vf]==-1)
InsertHeap(G[vfmin][j].vf);
else
upGrade(poz[G[vfmin][j].vf]);
}
}
}
void InsertHeap(int vf)
{
h[++lgh]=vf; poz[vf]=lgh;
upGrade(lgh);
}
void upGrade(int fiu)
{
int tata=fiu/2,aux;
while(tata&&dmin[tata]>dmin[fiu])
{
poz[h[fiu]]=tata; poz[h[tata]]=fiu;
aux=h[fiu]; h[fiu]=h[tata]; h[tata]=aux;
fiu=tata; tata=fiu/2;
}
}
void afisare()
{
int i;
for(i=1;i<=n;i++)
if(i!=x0)
{
if(dmin[i]==Infinit) fout<<0<<' ';
else fout<<dmin[i]<<' ';
}
}
int extrage()
{
int fiu,tata,aux;
int minim=h[1];
h[1]=h[lgh--]; poz[h[1]]=-1;
//downgrade
tata=1; fiu=2*tata;
while(fiu<=lgh)
{
if(fiu<lgh&&dmin[h[fiu]]>dmin[h[fiu+1]]) fiu++;
if(dmin[h[tata]]>dmin[h[fiu]])
{
poz[h[fiu]]=tata; poz[h[tata]]=fiu;
aux=h[fiu]; h[fiu]=h[tata]; h[tata]=aux;
tata=fiu; fiu=2*tata;
}
else break;
}
return minim;
}