Cod sursa(job #1157103)

Utilizator manutrutaEmanuel Truta manutruta Data 28 martie 2014 11:31:28
Problema Cuplaj maxim in graf bipartit Scor 20
Compilator cpp Status done
Runda Arhiva educationala Marime 2.46 kb
#include <iostream>
#include <fstream>
#include <bitset>
#include <vector>
#include <queue>

using namespace std;
typedef vector<int>::iterator iter;

#define INF 0x3f3f3f3f
#define MAXN 2005
#define MAXE 200005

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

int n, m, dest;
vector<int> G[MAXN];
bitset<MAXN> viz;
int cap[MAXN][MAXN], fl[MAXN][MAXN], t[MAXN];
queue<int> q;

bool bfs()
{
    viz.reset();
    viz[0] = true;
    q.push(0);

    while (!q.empty()) {
        int nd = q.front();
        q.pop();

        if (nd == dest) {
            continue;
        }

        for (iter it = G[nd].begin(); it != G[nd].end(); it++) {
            if (viz[*it] == true || cap[nd][*it] == fl[nd][*it]) {
                continue;
            }
            viz[*it] = true;

            t[*it] = nd;
            q.push(*it);
        }
    }
    return viz[dest];
}

int main()
{
    int e;
    f >> n >> m >> e;
    for (int i = 1, j = 1; i <= e; i++, j += 2) {
        int x, y;
        f >> x >> y; y += n;
        cap[x][y] = 1;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    for (int i = 1; i <= n; i++) {
        cap[0][i] = 1;
        G[0].push_back(i);
        G[i].push_back(0);
    }
    dest = n + m + 1;
    for (int i = n + 1; i <= n + m; i++) {
        cap[i][dest] = 1;
        G[i].push_back(dest);
        G[dest].push_back(i);
    }

    /*for (int i = 0; i <= n + m + 1; i++) {
        cout << i << ": ";
        for (iter it = G[i].begin(); it != G[i].end(); it++) {
            cout << *it << ' ';
        }
        cout << endl;
    }
    cout << endl << endl;*/

    int flux = 0;
    while (bfs()) {
        for (iter it = G[dest].begin(); it != G[dest].end(); it++) {
            if (viz[*it] == false) {
                continue;
            }
            t[dest] = *it;

            /*for (int i = dest; i != 0; i = t[i]) {
                cout << i << ' ';
            }
            cout << 0 << endl;*/

            int fmin = INF;
            for (int i = dest; i != 0; i = t[i]) {
                fmin = min(fmin, cap[t[i]][i] - fl[t[i]][i]);
            }
            //cout << fmin << endl << endl;

            for (int i = dest; i != 0; i = t[i]) {
                fl[t[i]][i] += fmin;
                fl[i][t[i]] -= fmin;
            }
            flux += fmin;
        }
    }

    g << flux << '\n';

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