Cod sursa(job #855182)

Utilizator raulstoinStoin Raul raulstoin Data 14 ianuarie 2013 19:06:05
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.51 kb
#include <cstdio>
#include <vector>
#include<queue>
#include<cstring>
#define NMax 1005
#define oo 2000000
using namespace std;
int C[NMax][NMax],F[NMax][NMax],Flow,TT[NMax],N,M,use[NMax];
vector <int> G[NMax];
queue<int> Q;

void Read()
{
	int i,x,y,z;
    freopen("maxflow.in","r",stdin);
    scanf("%d %d",&N,&M);
    for(i=1;i<=M;i++)
    {
        scanf("%d %d %d",&x,&y,&z);
        G[x].push_back(y);
        G[y].push_back(x);
        C[x][y]=z;
    }
}
  
int BFS()
{
    Q.push(1);
    memset(use,0,sizeof(use));
    use[1]=1;
    while(!Q.empty())
    {
        int nod=Q.front();Q.pop();
        if(nod==N) continue;
        for(unsigned int i=0;i<G[nod].size();i++)
		{
			int vec=G[nod][i];
			if(use[vec] || C[nod][vec]==F[nod][vec]) continue;
			use[vec]=1;
			Q.push(vec);
			TT[vec]=nod;
		}
    }
	return use[N];
}

void Solve()
{
	int fmin,nod;
    for(;BFS();)
		for(unsigned int i=0;i<G[N].size();i++)
		{
            int vec=G[N][i];
            if(!use[vec] || (C[vec][N]==F[vec][N])) continue;
            TT[N]=vec;
			fmin=oo;
            for(nod=N;nod!=1;nod=TT[nod])
                fmin=min(fmin,C[TT[nod]][nod]-F[TT[nod]][nod]);
            for(nod=N;nod!=1;nod=TT[nod])
			{
                F[TT[nod]][nod]+=fmin;
                F[nod][TT[nod]]-=fmin;
			}
            Flow+=fmin;
		}
}

void Print()
{
    freopen("maxflow.out","w",stdout);
    printf("%d\n",Flow);
}

int main()
{
    Read();
    Solve();
    Print();
    return 0;
}