Cod sursa(job #867599)

Utilizator SpiderManSimoiu Robert SpiderMan Data 29 ianuarie 2013 21:29:08
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.47 kb
# include <cstdio>
# include <cstring>
# include <queue>
# include <vector>
using namespace std;

const char *FIN = "maxflow.in", *FOU = "maxflow.out";
const int MAX = 1005;

vector <int> G[MAX];
int N, M, mf, C[MAX][MAX], F[MAX][MAX], T[MAX];

inline void getmin (int &a, int b) {
    a = a < b ? a : b;
}

inline int bfs (void) {
    memset (T, -1, sizeof (T)), T[1] = 0;
    queue <int> Q;
    for (Q.push (1); ! Q.empty (); Q.pop ()) {
        int X = Q.front ();
        for (vector <int> :: iterator i = G[X].begin (); i != G[X].end (); ++i)
            if (T[*i] == -1 && F[X][*i] < C[X][*i])
                Q.push (*i), T[*i] = X;
    }
    return T[N] != -1;
}

int main (void) {
    freopen (FIN, "r", stdin);

    scanf ("%d %d", &N, &M);
    for (int i = 1, x, y, z; i <= M; ++i) {
        scanf ("%d %d %d", &x, &y, &z);
        C[x][y] = z, G[x].push_back (y), G[y].push_back (x);
    }
    for (; bfs ();) {
        for (vector <int> :: iterator i = G[N].begin (); i != G[N].end (); ++i)
            if (F[*i][N] < C[*i][N]) {
                int fmin = C[*i][N] - F[*i][N];
                for (int j = *i; T[j]; j = T[j])
                    getmin (fmin, C[T[j]][j] - F[T[j]][j]);
                F[*i][N] += fmin, F[N][*i] -= fmin;
                for (int j = *i; T[j]; j = T[j])
                    F[T[j]][j] += fmin, F[j][T[j]] -= fmin;
                mf += fmin;
            }
    }
    fprintf (fopen (FOU, "w"), "%d", mf);
}