Cod sursa(job #584514)

Utilizator APOCALYPTODragos APOCALYPTO Data 25 aprilie 2011 18:17:54
Problema Flux maxim Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 2.83 kb
using namespace std;
#include<iostream>
#include<fstream>
#include<vector>
#define pb push_back
#define nmax 1010
struct nod{
int lg,c,f;};
int N,M;
vector<nod> G[nmax];
int ante[nmax], viz[nmax], q[nmax];
ofstream fout("maxflow.out");
bool BFS()
{
    int i;
    for(i=0;i<=N;i++)
    {
        q[i]=0;
        viz[i]=0;

    }
    int front=1;
    q[++q[0]]=1;
    viz[1]=1;
    int u;
    vector<nod>::iterator it;
    while(front<=q[0])
    {
        u=q[front++];

        for(it=G[u].begin();it<G[u].end();it++)
        {
            if(!viz[it->lg])
            {
                if(it->c>it->f)
                {
                    viz[it->lg]=1;
                    ante[it->lg]=u;
                    q[++q[0]]=it->lg;
                }
            }
        }
    }
    return viz[N];
}

void solve()
{
    int fmin,flow=0,i;
    vector<nod>::iterator it,jt;
    for(;BFS();)
    {
        for(it=G[N].begin();it<G[N].end();it++)
        {
            if(viz[it->lg])
            {
                   for(jt=G[it->lg].begin();jt<G[it->lg].end();jt++)
                   {
                       if(jt->lg==N)
                        break;
                   }
                   fmin=jt->c-jt->f;
                   for(i=it->lg;i!=1;i=ante[i])
                   {
                       for(jt=G[ante[i]].begin();jt<G[ante[i]].end();jt++)
                       {
                           if(jt->lg==i)
                              break;
                       }
                       fmin=min(fmin,jt->c-jt->f);
                   }
                   for(jt=G[it->lg].begin();jt<G[it->lg].end();jt++)
                   {
                       if(jt->lg==N)
                        break;
                   }
                   jt->f+=fmin;
                   it->f-=fmin;
                   for(i=it->lg;i!=1;i=ante[i])
                   {
                       for(jt=G[ante[i]].begin();jt<G[ante[i]].end();jt++)
                       {
                           if(jt->lg==i)
                              break;
                       }
                       jt->f+=fmin;
                       for(jt=G[i].begin();jt<G[i].end();jt++)
                       {
                           if(jt->lg==ante[i])
                              break;
                       }
                       jt->f-=fmin;

                   }
                   flow+=fmin;
                  // cout<<fmin<<" ";

            }
        }
    }

    fout<<flow<<"\n";
}

void cit()
{
    ifstream fin("maxflow.in");
    int i,x,y,z;
    fin>>N>>M;
    for(i=1;i<=M;i++)
    {
        fin>>x>>y>>z;
        G[x].pb((nod){y,z,0});
        G[y].pb((nod){x,0,0});
    }
    fin.close();
}

int main()
{
    cit();
    solve();
    fout.close();
    return 0;
}