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Cod sursa(job #451399)
/*
* File: main.cpp
* Author: virtualdemon
*
* Created on May 9, 2010, 2:49 PM
*/
#include <vector>
#include <cstdlib>
#include <fstream>
#define Nmax 200011
/*
*
*/
using namespace std;
typedef pair< int, int > pr;
int N;
int H[Nmax], P[Nmax], d[Nmax], apm[Nmax];
vector< pr > G[Nmax];
vector< pr >::const_iterator it, iend;
inline void DownHeap( int k )
{
for( int son=2*k; son <= N; k=son, son*=2 )
{
if( son < N && d[H[son]] > d[H[son+1]] )
++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[N]]=1;
P[H[1]]=-1;
H[1]=H[N];
--N;
DownHeap( 1 );
return r;
}
inline void push( int k )
{
H[++N]=k;
P[k]=N;
UpHeap( N );
}
int main(int argc, char** argv)
{
int NN, M, x, y, c, s=0;
ifstream in( "apm.in" );
for( in>>NN>>M; M; --M )
{
in>>x>>y>>c;
G[x].push_back( pr( y, c ) );
G[y].push_back( pr( x, c ) );
}
d[1]=0;
push( 1 );
while( N )
{
x=pop();
s+=d[x];
for( it=G[x].begin(), iend=G[x].end(); it < iend; ++it )
{
y=it->first, c=it->second;
if( -1 == P[y] )
continue;
if( 0 == P[y] )
{
d[y]=c;
apm[y]=x;
push(y);
}
if( d[y] > c )
{
d[y]=c;
apm[y]=x;
UpHeap( P[y] );
}
}
}
ofstream out( "apm.out" );
out<<s<<' '<<(NN-1)<<'\n';
for( x=2; x <= NN; ++x )
out<<x<<' '<<apm[x]<<'\n';
return (EXIT_SUCCESS);
}