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Cod sursa(job #551144)
#include <queue>
#include <vector>
#include <fstream>
#include <cstdlib>
#define N_MAX 1011
#define oo 1<<20
using namespace std;
int N;
vector< int > f;
int C[N_MAX][N_MAX], F[N_MAX][N_MAX];
vector< int > G[N_MAX];
inline int _min( int x, int y ) { return ( x <= y ? x : y ); }
bool findPath()
{
int x;
queue< int > Q;
vector< int >::const_iterator it, iend;
f.assign( N+1, -1 );
f[1]=-2;
for( Q.push(1); !Q.empty(); )
{
x=Q.front(); Q.pop();
if( N == x )
continue;
for( it=G[x].begin(), iend=G[x].end(); it < iend; ++it )
if( -1 == f[*it] && C[x][*it] > F[x][*it] )
{
f[*it]=x;
Q.push(*it);
}
}
if( -1 == f[N] )
return false;
return true;
}
int MaxFlow()
{
int min, x, s;
vector< int >::const_iterator it, iend;
for( s=0; findPath(); )
{
for( it=G[N].begin(), iend=G[N].end(); it < iend; ++it )
if( -1 != f[*it] && C[*it][N] > F[*it][N] )
{
f[N]=*it;
min=oo;
for( x=N; -2 != f[x]; x=f[x] )
min=_min( min, C[f[x]][x]-F[f[x]][x] );
for( x=N; -2 != f[x]; x=f[x] )
{
F[f[x]][x]+=min;
F[x][f[x]]-=min;
}
s+=min;
}
}
return s;
}
int main( void )
{
int M, x, y;
ifstream in( "maxflow.in" );
for( in>>N>>M; M; --M )
{
in>>x>>y;
in>>C[x][y];
G[x].push_back(y);
G[y].push_back(x);
}
f.resize( N+1 );
ofstream out( "maxflow.out" );
out<<MaxFlow()<<'\n';
return EXIT_SUCCESS;
}