Cod sursa(job #2273772)

Utilizator FunnyStockyMihnea Andreescu FunnyStocky Data 31 octombrie 2018 21:48:16
Problema Flux maxim Scor 20
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.63 kb
#include <fstream>
#include <vector>

using namespace std;

ifstream fin("maxflow.in");
ofstream fout("maxflow.out");

const int N=1000+5;

int n,m;
vector<pair<int,int>>g[N];

bool is[N],ie[N];
int ma[N];
int s=0;
int e=0;

inline void sloveMA(int nod)
{
    if(ma[nod]!=-1) return;
    for(auto &it:g[nod])
    {
        int nou=it.first;
        int co=it.second;
        if(nou==e)
        {
            ma[nod]=max(ma[nod],co);
        }
        else
        {
            sloveMA(nou);
            ma[nod]=max(ma[nod],min(ma[nou],co));
        }
    }
}

inline int fPath()
{
    for(int i=1;i<=n;i++) ma[i]=-1;
    ma[e]=0;
    sloveMA(s);
    int nod=s;
    while(1)
    {
        bool ok=0;
        for(int i=0;i<g[nod].size();i++)
        {
            int nou=g[nod][i].first;
            int co=g[nod][i].second;
            if(nou==e)
            {
                ok=1;
                break;
            }
            if(min(ma[nou],co)==ma[nod])
            {
                g[nod][i].second-=ma[s];
                nod=nou;
                break;
            }
        }
        if(ok) break;
    }
    return ma[s];
}

int main()
{
    fin>>n>>m;
    for(int i=1;i<=n;i++) is[i]=ie[i]=1;
    for(int i=1;i<=m;i++)
    {
        int a,b,x;
        fin>>a>>b>>x;
        g[a].push_back({b,x});
        is[b]=0;
        ie[a]=0;
    }
    for(int i=1;i<=n;i++)
    {
        if(is[i]) s=i;
        if(ie[i]) e=i;
    }
    int ans=0;
    while(1)
    {
        int x=fPath();
        if(!x) break;
        ans+=x;
    }
    fout<<ans<<"\n";
    return 0;
}