Cod sursa(job #1708830)

Utilizator UPB_Darius_Rares_SilviuPeace my pants UPB_Darius_Rares_Silviu Data 27 mai 2016 23:55:46
Problema Flux maxim Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.81 kb
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>
#define NMAX 1009
#define oo (1<<30)
using namespace std;

int N, M, cap[ NMAX ][ NMAX ], flow[ NMAX ][ NMAX ], d[ NMAX ], T[ NMAX ], inQ[ NMAX ];
queue<int> Q;
vector<int> G[NMAX];

bool BFS(int S, int D) {
    for (int i = 1; i <= N; ++i) {
        d[ i ] = oo;
        T[ i ] = 0;
    }

    d[ S ] = 0;
    T[ S ] = S;
    Q.push( S );
    inQ[ S ] = 1;

    while (!Q.empty()) {
        int node = Q.front();
        Q.pop();
        //inQ[ node ] = 0;

        for (vector<int>::iterator it = G[node].begin(); it != G[node].end(); ++it) {
            if (!T[ *it ] && flow[ node ][ *it ] < cap[ node ][ *it ]) {
                T[ *it ] = node;

                if (!inQ[ *it ]) {
                    inQ[ *it ] = 1;
                    Q.push( *it );
                }
            }
        }
    }

    return T[ D ];
}

int maxflow(int S, int D) {
    int sol = 0;

    while (BFS(S, D)) {
        int minFlow = oo;
        for (int node = D; node != S; node = T[ node]) {
            minFlow = min( minFlow, cap[ T[node] ][ node ] - flow[ T[node] ][ node ]);
        }

        if (minFlow > 0) {
            sol += minFlow;
            for (int node = D; node != S; node = T[ node]) {
                flow[ T[node] ][ node ] += minFlow;
                flow[ node ][ T[node] ] -= minFlow;
            }
        }
    }

    return sol;
}
int main() {
    freopen("maxflow.in", "r", stdin);
    freopen("maxflow.out", "w", stdout);

    scanf("%d%d", &N, &M);
    while (M--) {
        int x, y, c;
        scanf("%d%d%d", &x, &y, &c);
        cap[ x ][ y ] += c;
        G[ x ].push_back( y );
        G[ y ].push_back( x );
    }

    printf("%d\n", maxflow(1, N));

    return 0;
}