Cod sursa(job #2532528)

Utilizator AndreiD31Dragan Andrei AndreiD31 Data 27 ianuarie 2020 22:10:41
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.98 kb
#include <bits/stdc++.h>

using namespace std;

ifstream f("maxflow.in");
ofstream g("maxflow.out");

int n,ok,maxflow,tata[1010],flux[1010][1010],c[1010][1010],viz[1010];
queue <int> q;
vector <int> v[1010];

void BFS()
{
    int i,nod,vecin;
    for(i=1; i<=n; i++)viz[i]=0;

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

    while(!q.empty())
    {
        nod=q.front();
        for(i=0; i<v[nod].size(); i++)
        {
            vecin=v[nod][i];

            if(viz[vecin]==0 && flux[nod][vecin]<c[nod][vecin])
            {
                viz[vecin]=1;

                if(vecin!=n)
                {
                    tata[vecin]=nod;
                    q.push(vecin);
                }
            }

        }
        q.pop();
    }

    if(viz[n]==0)
    {
        ok=0;
        return;
    }
    else ok=1;

    /// dam update la matricea flux
    for(i=0; i<v[n].size(); i++)
    {
        /// iau vecinii inversi
        nod=v[n][i];
        if(viz[nod]==1 && flux[nod][n]<c[nod][n]) /// daca l-am vizitat in parcurgerea curenta si respecta conditia, atunci e bun
        {
            int flux_min=c[nod][n]-flux[nod][n];
            nod=v[n][i];
            while(tata[nod]!=0)
            {
                flux_min=min(flux_min,c[tata[nod]][nod]-flux[tata[nod]][nod]);
                nod=tata[nod];
            }

            maxflow+=flux_min;

            nod=v[n][i];
            flux[nod][n]+=flux_min;
            flux[n][nod]-=flux_min;
            while(tata[nod]!=0)
            {
                flux[tata[nod]][nod]+=flux_min;
                flux[nod][tata[nod]]-=flux_min;
                nod=tata[nod];
            }
        }
    }
}

int m,i,x,y,z;
int main()
{
    f>>n>>m;
    for(i=1; i<=m; i++)
    {
        f>>x>>y>>z;
        c[x][y]=z;
        v[x].push_back(y);
        v[y].push_back(x);
    }

    ok=1;
    while(ok)
    {
        ok=0;
        BFS();
    }

    g<<maxflow;
    return 0;
}