Cod sursa(job #717242)

Utilizator vendettaSalajan Razvan vendetta Data 19 martie 2012 19:24:14
Problema Flux maxim Scor 70
Compilator cpp Status done
Runda Arhiva educationala Marime 1.66 kb
#include <fstream>
#include <vector>
#include <queue>
#define nmax 1024

using namespace std;

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

int n, m, capacitate[nmax][nmax], flux[nmax][nmax];
int Min, flux_maxim;
int viz[nmax], T[nmax];
queue<int> q;
vector<int> gf[nmax];

void citeste(){

    f >> n >> m;
    for(int i=1; i<=m; i++){
        int x, y, c;//am capacitatea c in conducta x-> y;
        f >> x >> y >> c;
        gf[x].push_back(y);
        gf[y].push_back(x);
        capacitate[x][y] += c;
    }

}

int bfs(){

    for(int i=0; i<=n+1; i++) viz[i] = 0;

    q.push(1);//sursa = 1;
    viz[1] = 1;

    for(; q.size(); ){
        int nod = q.front();
        q.pop();
        for(int i=0; i<gf[nod].size(); i++){
            int vc = gf[nod][i];
            if (flux[nod][vc] == capacitate[nod][vc] || viz[vc] == 1) continue;
            q.push(vc);
            viz[vc] = 1;
            T[vc] = nod;
            //if (vc == n) return 1;//daca ajung la destinatie
        }
    }

    return viz[n];
}

void rezolva(){

    for(; bfs(); ){
        //cat timp exista drumuri de crestere aleg minimnul capacitatilor din acel drum;
        Min=(1<<30);
        for(int i=n; i!=1; i=T[i]){
            //am muchia T[i] -> i;
            Min = min(Min, capacitate[T[i]][i] - flux[T[i]][i]);
        }
        for(int i=n; i!=1; i=T[i]){
            flux[T[i]][i] += Min;//pe muchia T[i]->i
            flux[i][T[i]] -= Min;//pe muchia i->T[i];
            //initial flux[i][j] = 0;
        }
        flux_maxim+= Min;
    }

}

void scrie(){

    g << flux_maxim << "\n";

}

int main(){

    citeste();
    rezolva();
    scrie();

    f.close();
    g.close();

    return 0;

}