Cod sursa(job #1153250)

Utilizator ThomasFMI Suditu Thomas Thomas Data 25 martie 2014 12:41:45
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.5 kb
#include <fstream>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;

#define NMax 1005
#define inf 2100000000

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

int n,m;
vector<int> v[NMax];
int C[NMax][NMax],F[NMax][NMax];
int viz[NMax],ant[NMax];

int BFS()
{
    int s,i;
    queue<int> cd;
    cd.push(1);
    for(i=1;i<=n;i++) {viz[i]=ant[i]=0;}
    viz[1]=1;

    while(!cd.empty())
    {
        s=cd.front(); cd.pop();

        if(s!=n) for(i=0;i<(int)v[s].size();i++)
        if(!viz[v[s][i]] && F[s][v[s][i]]<C[s][v[s][i]])
        {
            viz[v[s][i]]=1;
            ant[v[s][i]]=s;
            cd.push(v[s][i]);
        }
    }

    return viz[n];
}

int main()
{
    int i,a,b,c;
    int flow;

    f>>n>>m;
    for(i=1;i<=m;i++)
    {
        f>>a>>b>>c;
        C[a][b]+=c;
        v[a].push_back(b);
        v[b].push_back(a);
    }

    int val,nod;

    for(flow=0;BFS();) for(i=0;i<(int)v[n].size();i++)
        if(viz[v[n][i]] && F[v[n][i]][n]<C[v[n][i]][n])
        {
            val=inf;
            nod=n;
            ant[n]=v[n][i];

            while(ant[nod])
            {
                val=min(val,C[ant[nod]][nod]-F[ant[nod]][nod]);
                nod=ant[nod];
            }

            nod=n;

            if(val) while(ant[nod])
            {
                F[ant[nod]][nod]+=val;
                F[nod][ant[nod]]-=val;
                nod=ant[nod];
            }

            flow+=val;
        }

    g<<flow<<"\n";

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