Cod sursa(job #1963835)

Utilizator nicu_serteSerte Nicu nicu_serte Data 12 aprilie 2017 20:24:01
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.72 kb
#include <fstream>
#include <vector>
#include <queue>
#include <climits>
using namespace std;
ifstream fin("maxflow.in");
ofstream fout("maxflow.out");
#define nmax 1024
#define inf INT_MAX
int n, m, c[nmax][nmax], tt[nmax], f[nmax][nmax];
bool viz[nmax]={0};
vector<int> g[nmax];
void citire()
{
    int i, x, y, z;
    fin>>n>>m;
    for(i=1; i<=m; i++)
    {
        fin>>x>>y>>z;
        g[x].push_back(y);
        g[y].push_back(x);
        c[x][y]+=z;
    }
    fin.close();
}
int bfs()
{
    queue<int> q;
    vector<int>::iterator it;
    int k;
    for(k=1; k<=n; k++)
        viz[k]=0;
    viz[1]=1; q.push(1);
    while(!q.empty())
    {
        k=q.front();
        q.pop();
        if(k==n)
            continue;
        for(it=g[k].begin(); it!=g[k].end(); it++)
        {
            if(viz[*it] || c[k][*it]==f[k][*it])
                continue;
            viz[*it]=1;
            tt[*it]=k;
            q.push(*it);
        }
    }
    return viz[n];
}
int main()
{
    int flow, fmin, nod;
    vector<int>::iterator it;
    citire();
    flow=0;
    while(bfs())
        for(it=g[n].begin(); it!=g[n].end(); it++)
        {
            if(f[*it][n]==c[*it][n] || !viz[*it])
                continue;
            fmin=inf;
            tt[n]=*it;
            for(nod=n; nod!=1; nod=tt[nod])
                fmin=min(fmin, c[tt[nod]][nod]-f[tt[nod]][nod]);
            if(fmin==0)
                continue;
            for(nod=n; nod!=1; nod=tt[nod])
                {
                    f[tt[nod]][nod]+=fmin;
                    f[nod][tt[nod]]-=fmin;
                }
                flow+=fmin;
        }
    fout<<flow<<'\n';
    fout.close();
    return 0;
}