Cod sursa(job #1701542)

Utilizator andreitulusAndrei andreitulus Data 13 mai 2016 13:39:21
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.69 kb
#include <fstream>
#include <vector>
#include <cstring>
 
const int NMAX = 1024;
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],flow,fmin,Q[NMAX],x,y,z,V,viz[NMAX];
vector <int> v[NMAX];
 
int minim(int a, int b)
{
    if (a < b) return a;
    return b;
}
 
int BFS()
{
    int V,nod;
    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] = true;
            TT[V] = nod;
            Q[ ++Q[0] ] = V;
        }
    }
 
    return viz[N];
}
 
int main()
{
    f >> N >> M;
 
    for (int i = 1; i <= M; ++i)
    {
        f >> x >> y >> z;
        C[x][y] = z;
        v[x].push_back(y);
        v[y].push_back(x);
    }
 
    for (flow = 0; BFS();)
    {
        for (int i = 0; i < v[N].size(); ++i)
        {
            V = v[N][i];
            TT[N] = V;
            if (F[V][N] == C[V][N] || !viz[V])
                continue;
 
            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;
}