Cod sursa(job #1626635)

Utilizator LolkekzorChiorean Tudor Lolkekzor Data 3 martie 2016 10:48:16
Problema Flux maxim Scor 30
Compilator cpp Status done
Runda Arhiva educationala Marime 1.69 kb
#include <fstream>
#include <list>
#include <queue>
using namespace std;
ifstream fin("maxflow.in");
ofstream fout("maxflow.out");

int n, m, x, y, c, i, crt, mini, flow;
int flowMat[1010][1010], arbore[1010];
bool ok = true;
list<int> graf[1010];
queue<int> Q;

void makeArb() {
    for (int i = 1 ; i <= n ; i++) arbore[i] = 0;

    Q.push(1);
    while (!Q.empty()) {
        crt = Q.front(); Q.pop();
        for (list<int>::iterator it = graf[crt].begin() ; it != graf[crt].end() ; it++) {
            if (arbore[*it] == 0 && flowMat[crt][*it] > 0 && *it != n && *it != 1) {
                arbore[*it] = crt;
                Q.push(*it);
            }
        }
    }
}

int getMin(int nod) {
    int ans = flowMat[nod][n];
    while (arbore[nod] != 0) {
        ans = min(ans, flowMat[ arbore[ nod ] ][ nod ]);
        nod = arbore[nod];
    }
    return ans;
}

void saturate(int nod, int val) {
    flowMat[i][nod] -= val;
    while (arbore[nod] != 0) {
        flowMat[ arbore[ nod ] ][ nod ] -= val;
        flowMat[ nod ][ arbore[ nod ] ] += val;
        nod = arbore[nod];
    }
}

int main()
{
    fin>>n>>m;
    for (i = 1 ; i <= m ; i++) {
        fin>>x>>y>>c;
        graf[x].push_back(y);
        graf[y].push_back(x);
        flowMat[x][y] = c;
    }

    flow = flowMat[1][n];
    flowMat[1][n] = 0;

    while(ok) {
        ok = false;
        makeArb();
        for (i = 2 ; i < n ; i++) {
            if (arbore[i] != 0 && flowMat[i][n] > 0) {
                ok = true;
                mini = getMin(i);
                flow += mini;
                saturate(i, mini);
            }
        }
    }

    fout<<flow;

return 0;
}