Cod sursa(job #2664843)

Utilizator Radu_FilipescuFilipescu Radu Radu_Filipescu Data 29 octombrie 2020 15:59:18
Problema Arbore partial de cost minim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.54 kb
#include <bits/stdc++.h>

using namespace std;

ifstream fin( "apm.in" );
ofstream fout( "apm.out" );

const int NMAX = 200005;

int N, M;
struct edg
{
    int a, b;
    int d;

    bool operator < ( const edg & E ) {
        return d < E.d;
    }
} A[2 * NMAX];

int m[NMAX];
int sz[NMAX];

vector <pair<int,int> > sol;

int Find( int a ) {
    int ra = a;

    while( m[ra] != ra )
        ra = m[ra];

    while( a != m[a] ) {
        int aux = m[a];
        m[a] = ra;
        a = aux;
    }
    return ra;
}

void Union( int a, int b ) {
    int ra = Find( a );
    int rb = Find( b );

    if( sz[ra] < sz[rb] ) swap( ra, rb );

    sz[ra] += sz[rb];
    m[rb] = ra;
}

void Read() {
    fin >> N >> M;

    int a, b, d;
    for( int i = 1; i <= M; ++i ) {
        fin >> a >> b >> d;

        A[i].a = a;
        A[i].b = b;
        A[i].d = d;
    }
}

void Do()
{
    sort( &A[1], &A[M + 1] );

    for( int i = 1; i <= N; ++i )
        sz[i] = 1, m[i] = i;

    int added = 0;
    int cost = 0;

    for( int i = 1; i <= M && added < N - 1; ++i ) {
        int fa = Find( A[i].a ), fb = Find( A[i].b );

        if( fa != fb ) {
            ++added;
            Union( fa, fb );
            cost += A[i].d;
            sol.push_back( { A[i].a, A[i].b } );
        }
    }

    fout << cost << '\n' << added << '\n';
    for( int i = 0; i < sol.size(); ++i )
        fout << sol[i].first << ' ' << sol[i].second << '\n';

}

int main()
{
    Read();
    Do();

    return 0;
}