Cod sursa(job #988605)

Utilizator classiusCobuz Andrei classius Data 23 august 2013 14:00:04
Problema Flux maxim Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.69 kb
#include <fstream>
#include <vector>
#include <algorithm>
#define ds (v[i][j])
#define sd (rv[i][j])
using namespace std;

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

struct crd{
    crd(int a,int b):x(a),y(b){}
    int x,y;
};

int n,m,s;
vector<int> v[1001],rv[1001],fl[1001],a[1001],pz[1001];
bool vs[1001];
vector<int> sl;
vector<crd> inc;
vector<bool> wt;

void max_flow(int i){

    if(i==n){
        int mn=*min_element(sl.begin(),sl.end());

        for(unsigned j=0;j<inc.size();j++){
            if(wt[j])
                a[inc[j].x][inc[j].y]+=mn;
            else
                a[inc[j].x][inc[j].y]-=mn;
        }
        s+=mn;

        return;
    }

    for(unsigned j=0;j<v[i].size();j++){
        if(!vs[ds]&&a[i][j]<fl[i][j]){
            vs[ds]=1;
            sl.push_back(fl[i][j]-a[i][j]);
            inc.push_back(crd(i,j));
            wt.push_back(1);
            max_flow(ds);
            vs[ds]=0;
            sl.pop_back();
            inc.pop_back();
            wt.pop_back();
        }
    }

    for(unsigned j=0;j<rv[i].size();j++){
        if(!vs[sd]&&a[sd][pz[i][j]]){
            vs[sd]=1;
            sl.push_back(a[sd][pz[i][j]]);
            inc.push_back(crd(i,pz[i][j]));
            wt.push_back(0);
            max_flow(sd);
            vs[sd]=0;
            sl.pop_back();
            inc.pop_back();
            wt.pop_back();
        }
    }

    return;
}

int main()
{
    f>>n>>m;

    for(int i=1;i<=m;i++){
        int x,y,flo;
        f>>x>>y>>flo;
        v[x].push_back(y);
        rv[y].push_back(x);
        pz[y].push_back(v[x].size()-1);
        fl[x].push_back(flo);
        a[x].push_back(0);
    }

    max_flow(1);

    g<<s;

    return 0;
}