Cod sursa(job #584521)

Utilizator ArdeleanAndreiArdelean Andrei ArdeleanAndrei Data 25 aprilie 2011 18:42:00
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.88 kb
#include <stdio.h>
#include <vector>

using namespace std;

#define NMAX 1024
#define pb push_back
#define sz size()
#define mp make_pair
#define INF 0x3f3f3f3f

int C[NMAX][NMAX];//valori max graf
int F[NMAX][NMAX];//graf rezidual.
int TT[NMAX];// drum parcurs - din nodul TT[x] se merge in x
vector<int> G[NMAX];//nod-legarura
int N, M;//noduri si legaruri
int cd[NMAX];//coada
bool viz[NMAX];

bool BF()
{
	int i, j, nod, V;

	cd[0] = 1;//lungimea cozii
	cd[1] = 1;//element al cozii
	memset(viz, 0, sizeof(viz));
	viz[1] = true;

	for (i = 1; i <= cd[0]; i++)//parcurege coada
	{
		nod = cd[i];
		if (nod == N) continue;
		for (j = 0; j < (int)G[nod].sz; j++) 
			{
				V = G[nod][j];
				if (C[nod][V] == F[nod][V] || viz[V]) continue;
				viz[V] = true;
				cd[ ++cd[0] ] = V;
				TT[V] = nod;
			}
	}

	return viz[N];
}

int main()
{
	freopen("maxflow.in", "r", stdin);
	freopen("maxflow.out", "w", stdout);

	int i, flow, fmin, x, y, z, nod;

	scanf("%d %d ", &N, &M);

	for (i = 1; i <= M; i++)
	{
		scanf("%d %d %d ", &x, &y, &z);
		C[x][y] += z;
		G[x].pb(y);
		G[y].pb(x);
	}
	
	flow = 0;//flux maxim
	while( BF() )// cat timp gaseste drum
		for (i = 0; i < (int)G[N].sz; i++)//i parcurge nodurile cu care se leaga nodul Destinatie
		{
			nod = G[N][i];// nod curent
			if (F[nod][N] == C[nod][N] || !viz[nod]) continue;//daca legatura nod destinatie e saturata sau nu a fost accesata
			TT[N] = nod;
			
			fmin = INF;
			for (nod = N; nod != 1; nod = TT[nod])  // parcurge drumul si cauta valoarea maxima pe care o poate adauga fluxului total
				fmin = min(fmin, C[ TT[nod] ][nod] - F[ TT[nod] ][nod]);
			if (fmin == 0) continue;//inseaman ca nu se mai poate adauga nimic accestui drum
			
			for (nod = N; nod != 1; nod = TT[nod])//creste fluxul rezidual
			{
				F[ TT[nod] ][nod] += fmin;
				F[nod][ TT[nod] ] -= fmin;
			}

			flow += fmin;//flux maxim += flux drum
		}

	printf("%d ", flow);
	return 0;
}