Cod sursa(job #1919548)

Utilizator TibixbAndrei Tiberiu Tibixb Data 9 martie 2017 20:00:52
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.89 kb
#include<fstream>
#include<vector>
#include<queue>
#include<cstring>
#define NMAX 1005
using namespace std;
vector<int> G[NMAX];
queue<int> q;
int n, m, x, y, z;
bool u[NMAX];
int nod, minim, flux;
int C[NMAX][NMAX];
int F[NMAX][NMAX];
int T[NMAX];
ifstream cin("maxflow.in");
ofstream cout("maxflow.out");
void reinit()
{
    memset(u, 0, sizeof(u));
}
bool bfs()
{
    reinit();

    q.push(1);
    u[1] = 1;

    while(!q.empty())
    {
        nod = q.front();
        q.pop();
        for(int i = 0; i < G[nod].size(); i++)
        {
            int fiu = G[nod][i];
            if(u[fiu] == 0 && C[nod][fiu] - F[nod][fiu] > 0)
            {
                q.push(fiu);
                u[fiu] = 1;
                T[fiu] = nod;
            }
        }
    }
    return u[n] == 1;
}
void flow_update(int tata, int fiu, int minim)
{
    F[tata][fiu] += minim;
    F[fiu][tata] -= minim;
}
void flux_maxim()
{
    while(bfs())
    {
        for(int i = 0; i < G[n].size(); i++)
        {
            int fiu = G[n][i];
            if(u[fiu] == 1)
            {
                minim = C[fiu][n] - F[fiu][n];
                for(; T[fiu] != 0 && minim != 0; fiu = T[fiu])
                {
                    minim = min(C[T[fiu]][fiu] - F[T[fiu]][fiu], minim);
                }
            }
            if(minim != 0)
            {
                flux += minim;
                fiu = G[n][i];
                flow_update(fiu, n, minim);
                for(; T[fiu] != 0; fiu = T[fiu])
                {
                    flow_update(T[fiu], fiu, minim);
                }
            }
        }
    }
}
int main()
{
    cin >> n >> m;
    for(int i = 1; i <= m; i++)
    {
        cin >> x >> y >> z;

        G[x].push_back(y);
        C[x][y] = z;

        G[y].push_back(x);
    }
    flux_maxim();
    cout << flux;
    return 0;
}