Cod sursa(job #688012)

Utilizator alexdmotocMotoc Alexandru alexdmotoc Data 22 februarie 2012 22:39:24
Problema Flux maxim Scor 30
Compilator cpp Status done
Runda Arhiva educationala Marime 1.8 kb
#include <cstdio>
#include <vector>
#include <queue>
#include <algorithm>
#include <cstring>
#include <string>

using namespace std;

#define maxN 1005
#define INF 0x3f3f3f3f
#define PB push_back

int N , M , cap[maxN][maxN] , flux[maxN][maxN] , tata[maxN] , sol;
bool viz[maxN];


vector <int> lista[maxN];
queue <int> Q;


int am_flux ()
{
	Q.push (1);
	tata[1] = 1;
	
	memset (viz , 0 , sizeof (viz));
	
	viz[1] = true;
	
	
	while (!Q.empty ())
	{
		int nod = Q.front ();
		Q.pop ();
		
		if (nod == N)
			continue;
		
		for (unsigned int i = 0 ; i < lista[nod].size () ; ++i)
		{
			int nodcur = lista[nod][i];
			
			
			if (cap[nod][nodcur] - flux[nod][nodcur] == 0)
				continue;
			
			
			if (viz[nodcur])
				continue;
			
			tata[nodcur] = nod;
			viz[nodcur] = true;
			
			Q.push (nodcur);
		}
	}
	
	
	if (!viz[N])
		return 0;
	
	
	for (unsigned int i = 0 ; i < lista[N].size () ; ++i)
	{
	
		int nod = lista[N][i] , minim = INF;
		
		
		if (cap[nod][N] - flux[nod][N] == 0)
			continue;
		
		if (!viz[nod])
			continue;
		
		
		
		tata[N] = nod;
		
		
		while (nod != 1)
		{
			minim = min (minim , cap[tata[nod]][nod] - flux[tata[nod]][nod]);
			
			nod = tata[nod];
		}
		
		
		nod = N;
		
		while (nod != 1)
		{
			flux[tata[nod]][nod] += minim;
			flux[nod][tata[nod]] -= minim;
			
			nod = tata[nod];
		}
		
		sol += minim;
	}
	
	return 1;
}


int main ()
{
	freopen ("maxflow.in" , "r" , stdin);
	freopen ("maxflow.out" , "w" , stdout);
	
	scanf ("%d %d" , &N , &M);
	
	int x , y , z;
	
	for (int i = 1 ; i <= M ; ++i)
	{
		scanf ("%d %d %d" , &x , &y , &z);
		
		lista[x]. PB (y);
		lista[y]. PB (x);
		
		cap[x][y] = z;
	}
	
	
	while (am_flux ());
	
	
	printf ("%d" , sol);
	
	
	return 0;
}