Cod sursa(job #1005568)

Utilizator FlameingoAiordachioaei Marius Flameingo Data 5 octombrie 2013 11:54:45
Problema Flux maxim Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.66 kb
#include <cstdio>
#include <vector>
#include <queue>
#include <bitset>
#include <algorithm>
using namespace std;

const int NMAX = 1003, INFI = 2e9;

vector <int> G[NMAX];
queue <int> Q;
bitset <NMAX> nviz;
int cap[NMAX][NMAX], res[NMAX][NMAX], prev[NMAX], N;

bool BFS () {

    int node;
    vector <int> :: iterator i;
    nviz.set ();
    Q.push (1);
    while (!Q.empty ()) {
        node = Q.front ();
        Q.pop ();
        nviz[node] = 0;
        if (node == N)
            continue;
        for (i = G[node].begin (); i != G[node].end (); ++i)
            if (nviz[*i] && cap[node][*i] != res[node][*i])
                prev[*i] = node,
                Q.push (*i);
    }
    return !nviz[N];

}

int main () {

    freopen ("maxflow.in", "r", stdin);
    freopen ("maxflow.out", "w", stdout);
    int M, a, b, i, node, _min, max_flow = 0;
    vector <int> :: iterator j;
    scanf ("%d%d", &N, &M);
    for (i = 1; i <= M; ++i)
        scanf ("%d%d", &a, &b),
        scanf ("%d", &cap[a][b]),
        G[a].push_back (b),
        G[b].push_back (a);
    while (BFS ())
        for (j = G[N].begin (); j != G[N].end (); ++j) {
            if (nviz[*j] || cap[*j][N] == res[*j][N])
                continue;
            _min = INFI;
            prev[N] = *j;
            for (node = N; node != 1; node = prev[node])
                _min = min (_min, cap[prev[node]][node] - res[prev[node]][node]);
            for (node = N; node != 1; node = prev[node])
                res[prev[node]][node] += _min,
                res[node][prev[node]] -= _min;
            max_flow += _min;
        }
    printf ("%d", max_flow);

}