Cod sursa(job #2840396)

Utilizator cdenisCovei Denis cdenis Data 27 ianuarie 2022 18:17:57
Problema Flux maxim Scor 20
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.46 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream fin("maxflow.in");
ofstream fout("maxflow.out");

const int MAX=1005;
const int INF=1e9;
int n,m,a,b,c,t[MAX],viz[MAX],flux,fmax,cap[MAX][MAX],nod;
bool ok;
vector < int > v[MAX];

bool BFS()
{
    queue < int > q;
    for(int i=1;i<=n;i++)
        viz[i]=t[i]=0;
    q.push(1);
    viz[1]=1;
    ok=0;
    while(!q.empty() && !ok)
    {
        nod=q.front();
        q.pop();
        if(nod==n)
            continue;
        for(auto vec : v[nod])
            if(!viz[vec] && cap[nod][vec]>0)
            {
                viz[vec]=1;
                q.push(vec);
                t[vec]=nod;
            }
    }
    return viz[n];
}

int main()
{
    fin >> n >> m;
    while(m--)
    {
        fin >> a >> b >> c;
        v[a].push_back(b);
        v[b].push_back(a);
        cap[a][b]=c;
    }
    while(BFS())
        for(auto vec : v[n])
        {
            flux=INF;
            nod=vec;
            while(nod!=1)
            {
                if(cap[t[nod]][nod]<flux)
                    flux=cap[t[nod]][nod];
                nod=t[nod];
            }
            nod=vec;
            while(nod!=1)
            {
                cap[nod][t[nod]]+=flux;
                cap[t[nod]][nod]-=flux;
                nod=t[nod];
            }
            fmax+=flux;
        }
    fout << fmax;
    return 0;
}