Cod sursa(job #3342948)

Utilizator Elena_CretuCretu Elena Elena_Cretu Data 26 februarie 2026 10:35:43
Problema Arbore partial de cost minim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.95 kb
#include <fstream>
#include <queue>
#define NMAX 200002
#define MMAX 400002
using namespace std;
ifstream fin ("apm.in");
ofstream fout ("apm.out");
struct muchie {int x,y,c;
                   friend bool operator < (muchie a, muchie b);
                };
int n,m,costmin;
int tata[NMAX];
int h[NMAX]; //h[x]=inaltimea arborelui cu radac

muchie apm[NMAX];

bool operator < (muchie a, muchie b)
{
    return a.c > b.c;
}

int Find(int x);
void Union(int x,int y);
void citire();
void kruskal();
void afisare()
{   int i;
    fout<<costmin<<'\n'<<n-1<<'\n';
    for (i=1; i<n; i++)
        fout<<apm[i].x<<' '<<apm[i].y<<'\n';
}
priority_queue<muchie> H;
int main()
{
    citire();
    kruskal();
    afisare();
    return 0;
}
void citire()
{   int i,x,y,c;
    muchie aux;
    fin>>n>>m;
    for (i=0; i<m; i++)
    {
        fin>>aux.x>>aux.y>>aux.c;
        H.push(aux);
    }
}
int Find(int x)
{   int rx,y;
    //determin radacina arborelui
    rx=x;
    while (tata[rx]) rx=tata[rx];
    //rx este radacina
    //compresez drumul de la x la rx;
    //fiecare nod de pe acest drum devine fiu al lui rx
    while (tata[x] && tata[x]!=rx)
    {
         y=tata[x];
         tata[x]=rx;
         x=y;
    }
    return rx;
}
void Union(int x,int y)
//reuneste arborele in care se afla x cu arborele in care se afla y
{   int rx,ry;
    rx=Find(x); ry=Find(y);
    if (h[rx]<h[ry])
        //rx devine fiul lui ry
        tata[rx]=ry;
    else
        if (h[ry]<h[rx]) //ry devine fiul lui rx
            tata[ry]=rx;
        else //egalitate
        {
            tata[ry]=rx;
            h[rx]++;
        }
}
void kruskal()
{   muchie aux;
    int rx,ry,nrsel=0;
    while (nrsel<n-1)
    {
        aux=H.top(); H.pop();
        rx=Find(aux.x); ry=Find(aux.y);
        if (rx!=ry)
        {
            costmin+=aux.c;
            apm[++nrsel]=aux;
            Union(rx,ry);
        }

    }
}