Cod sursa(job #513458)

Utilizator gabipurcaruGabi Purcaru gabipurcaru Data 15 decembrie 2010 21:45:35
Problema Flux maxim Scor 70
Compilator cpp Status done
Runda Arhiva educationala Marime 1.11 kb
// infoarena: problema/maxflow //
#include <fstream>
#include <queue>
#include <iostream>
#include <cstring>
#define MAXN 1010
using namespace std;

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

int f[MAXN][MAXN],c[MAXN][MAXN],i,j,n,m,a,b,s,d,t[MAXN],r,flux;
vector<int> g[MAXN];
deque<int> q;
vector<int>::iterator it, fin;

inline int bf()
{
    memset(t, 0, sizeof(t[0]) * (n+1));
    q.resize(0);
	q.push_back(s);
	int nod,v;
	while(!q.empty())
	{
		nod = q.front(); q.pop_front();
        fin = g[nod].end();
        for(it = g[nod].begin(); it!=fin; ++it)
        {
            v = *it;
			if(!t[v] && c[nod][v] > f[nod][v])
			{
				t[v] = nod, q.push_back(v);
				if(v == d)
					return 1;
			}
        }
	}
	return 0;
}

int main()
{
	in>>n>>m;
	for(i=1; i<=m; i++)
    {
		in>>a>>b;
        in>>c[a][b];
        g[a].push_back(b);
        g[b].push_back(a);
    }
	
	s=1, d=n;
	
	for(flux=0; bf(); flux += r)
	{
		r = 1<<29;
        for(i=d; i!=s; i=t[i])
            r = min(r, c[t[i]][i] - f[t[i]][i]);
        for(i=d; i!=s; i=t[i])
		{
			f[t[i]][i] += r;
			f[i][t[i]] -= r;
		}
	}
	
	out<<flux;
	
	return 0;
}