Mai intai trebuie sa te autentifici.
Cod sursa(job #1204481)
Utilizator | Data | 3 iulie 2014 00:14:53 | |
---|---|---|---|
Problema | Flux maxim | Scor | 40 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 1.9 kb |
#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <algorithm>
using namespace std;
const int Nmax = 1e3 + 2;
vector <int> G[Nmax];
int C[Nmax][Nmax];
int F[Nmax][Nmax];
int father[Nmax];
int coada[Nmax];
int N, M;
bool BFS( int S, int D )
{
int st, dr;
coada[st = dr = 1] = S;
father[S] = S;
fill( father + 1, father + N + 1, 0 );
while ( st <= dr )
{
int nod = coada[ st++ ];
for ( auto vecin: G[nod] )
{
if ( father[vecin] == 0 && C[nod][vecin] > F[nod][vecin] )
{
father[vecin] = nod;
coada[ ++dr ] = vecin;
if ( vecin == D )
return true;
}
}
}
return false;
}
int Edmonds_Karp( int S, int D )
{
int flow = 0;
while ( BFS( S, D ) )
{
for ( auto vecin: G[D] )
{
if ( father[vecin] == 0 || F[vecin][D] >= C[vecin][D] )
continue;
father[D] = vecin;
int flow_min = 1e9;
for ( int node = D; node != S; node = father[ node ] )
flow_min = min( flow_min, C[ father[node] ][node] - F[ father[node] ][node] );
if ( flow_min == 0 )
continue;
for ( int node = D; node != S; node = father[ node ] )
{
F[ father[node] ][node] += flow_min;
F[node][ father[node] ] -= flow_min;
}
flow += flow_min;
}
}
return flow;
}
void add_edge( int i, int j, int c )
{
G[i].push_back( j );
C[i][j] = c;
}
int main()
{
ifstream in("maxflow.in");
ofstream out("maxflow.out");
in >> N >> M;
for ( int i = 1, a, b, c; i <= M; ++i )
{
in >> a >> b >> c;
add_edge( a, b, c );
add_edge( b, a, 0 );
}
out << Edmonds_Karp( 1, N ) << "\n";
return 0;
}