Cod sursa(job #1166514)

Utilizator ArmandNMArmand Nicolicioiu ArmandNM Data 3 aprilie 2014 17:18:48
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.74 kb
#include <fstream>
#include <vector>
#include <cstring>

const int NMAX = 1005;
const int inf = 0x3f3f3f3f;

using namespace std;
ifstream f("maxflow.in");
ofstream g("maxflow.out");

int N,M,F[NMAX][NMAX],C[NMAX][NMAX],TT[NMAX],Q[NMAX],fmin,flow,x,y,z,viz[NMAX],V;
vector <int> v[NMAX];

int minim(int a, int b)
{
    if (a < b)
        return a;
    return b;
}

int BFS()
{
    int nod, V;
    Q[0] = 1;
    Q[1] = 1;
    memset(viz, 0, sizeof(viz));
    viz[1] = 1;

    for (int i = 1; i <= Q[0]; ++i)
    {
        nod = Q[i];
        if (nod == N) continue;
        for (int j = 0; j < v[nod].size(); ++j)
        {
            V = v[nod][j];
            if (viz[V] || F[nod][V] == C[nod][V])
                continue;
            viz[V] = 1;
            Q[ ++Q[0] ] = V;
            TT[V] = nod;
        }
    }

    return viz[N];
}

int main()
{
    f >> N >> M;
    for (int i = 1; i <= M; ++i)
    {
        f >> x >> y >> z;
        v[x].push_back(y);
        v[y].push_back(x);
        C[x][y] = z;
    }

    while (BFS())
    {
        for (int i = 0; i < v[N].size(); ++i)
        {
            V = v[N][i];
            if (!viz[V] || F[V][N] == C[V][N])
                continue;
            TT[N] = V;

            fmin = inf;

            for (int j = N; j != 1; j = TT[j])
            {
                fmin = minim(fmin, C[ TT[j] ][j] - F[ TT[j] ][j]);
            }

            if (fmin == 0) continue;

            for (int j = N; j != 1; j = TT[j])
            {
                F[ TT[j] ][j] += fmin;
                F[j][ TT[j] ] -= fmin;
            }

            flow += fmin;
        }
    }

    g << flow;
    f.close();
    g.close();
    return 0;
}