Cod sursa(job #1347067)

Utilizator somuBanil Ardej somu Data 18 februarie 2015 19:28:41
Problema Flux maxim Scor 10
Compilator cpp Status done
Runda Arhiva educationala Marime 1.68 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define nmax 1005

using namespace std;

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

int n, m, fMax;
int capacitate[nmax][nmax], flux[nmax][nmax];
int tata[nmax];
bool viz[nmax];

vector <int> GF[nmax];
queue <int> q;

int bfs() {
    
    for (int i = 1; i <= n+1; i++)
        viz[i] = 0;
    
    viz[1] = 1;
    q.push(1);
    
    while (!q.empty()) {
        int nod = q.front();
        q.pop();
        for (int i = 0; i < GF[nod].size(); i++) {
            int vecin = GF[nod][i];
            if (viz[vecin] || capacitate[nod][vecin] == flux[nod][vecin]) continue;
            tata[vecin] = nod;
            viz[vecin] = 1;
            q.push(vecin);
        }
    }
    
    return viz[n];
}

int main() {
    
    fin >> n >> m;
    
    for (int i = 1; i <= m; i++) {
        int x, y, z;
        fin >> x >> y >> z;
        GF[x].push_back(y);
        GF[y].push_back(x);
        capacitate[x][y] = z;
    }
    
    while (bfs()) {
        for (int i = 0; i < GF[n].size(); i++) {
            int vecin = GF[n][i];
            if (!viz[vecin] || capacitate[vecin][n] == flux[vecin][n]) continue;
            tata[n] = vecin;
            int fMin = 110005;
            for (int nod = n; nod != 1; nod = tata[nod])
                fMin = min(fMin, capacitate[tata[nod]][nod] - flux[tata[nod]][nod]);
            if (fMin == 0) continue;
            fMax += fMin;
            for (int nod = n; nod != 1; nod = tata[nod])
                flux[tata[nod]][nod] += fMin,
                flux[nod][tata[nod]] -= fMin;
        }
    }
     
    fout << fMax << "\n";
    
    fin.close();
    fout.close();
    
    return 0;
}