Cod sursa(job #438019)
/*
* File: main.cpp
* Author: VirtualDemon
*
* Created on April 10, 2010, 9:57 AM
*/
#include <vector>
#include <cstdlib>
#include <fstream>
#include <algorithm>
#define Nmax 200001
/*
*
*/
using namespace std;
typedef pair< int, int > pr;
int N=1;
int H[Nmax], P[Nmax], D[Nmax], apm[Nmax];
vector< vector< pr > > G;
vector< pr >::const_iterator it, iend;
inline void DownHeap( int k )
{
for( int son=2*k; son <= N; k=son, son=2*k )
{
if( son < N && D[H[son+1]] < D[H[son]] )
++son;
if( D[H[k]] <= D[H[son]] )
return;
swap( H[k], H[son] );
P[H[k]]=k;
P[H[son]]=son;
}
}
inline void UpHeap( int k )
{
for( int key=D[H[k]], f=k/2; k > 1 && key < D[H[f]]; k=f, f/=2 )
{
swap( H[k], H[f] );
P[H[k]]=k;
P[H[f]]=f;
}
}
inline int pop( void )
{
int r=H[1];
P[H[1]]=P[H[N]];
H[1]=H[N];
--N;
DownHeap( 1 );
return r;
}
inline void push( int k )
{
H[++N]=k;
P[k]=N;
UpHeap(N);
}
int main( void )
{
int n, M, x, y, c, s=0;
ifstream in( "apm.in" );
in>>n;
G.resize(n);
for( in>>M; M; --M )
{
in>>x>>y>>c;
--x, --y;
G[x].push_back( pr( y, c ) );
G[y].push_back( pr( x, c ) );
}
while( N )
{
x=pop();
s+=D[x];
P[x]=-1;
for( it=G[x].begin(), iend=G[x].end(); it < iend; ++it )
if( -1 != P[it->first] )
{
y=it->first, c=it->second;
if( !P[y] )
{
D[y]=c;
apm[y]=x+1;
push(y);
continue;
}
if( D[y] > c )
{
D[y]=c;
apm[y]=x+1;
UpHeap( P[y] );
}
}
}
ofstream out( "apm.out" );
out<<s<<'\n'<<(n-1)<<'\n';
for( x=1; x < n; ++x )
out<<(x+1)<<' '<<apm[x]<<'\n';
return EXIT_SUCCESS;
}