Cod sursa(job #581166)

Utilizator mihai995mihai995 mihai995 Data 13 aprilie 2011 20:37:55
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.04 kb
#include <fstream>
using namespace std;

const int N=1001,inf=1<<30;
int cap[N][N],v[N],T[N],flux[N][N],n;
bool use[N];

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

bool bfs(int X,int Y)
{
	int x,y,st=0,dr=0;
	v[++dr]=X;
	for (x=1;x<=n;x++)
	{
		use[x]=false;
		T[x]=0;
	}
	while (st<dr)
	{
		x=v[++st];
		use[x]=true;
		for (y=1;y<=n;y++)
		{
			if (!use[y] && cap[x][y]>flux[x][y])
			{
				if (y!=Y)
				{
					v[++dr]=y;
					T[y]=x;
				}
				use[y]=true;
			}
		}
	}
	return use[Y];
}

int max_flow(int X,int Y)
{
	int M,i,j,flow=0;
	while (bfs(X,Y))
		for (i=X;i<Y;i++)
		{
			M=cap[i][Y]-flux[i][Y];
			if (!M)
				continue;
			for (j=i;j>X;j=T[j])
				M=min(M,cap[T[j]][j]-flux[T[j]][j]);
			if (!M)
				continue;
			T[Y]=i;
			for (j=Y;j!=X;j=T[j])
			{
				flux[T[j]][j]+=M;
				flux[j][T[j]]-=M;
			}
			flow+=M;
		}
	return flow;
}

int main()
{
	int m,x,y,c;
	in>>n>>m;
	while (m--)
	{
		in>>x>>y>>c;
		cap[x][y]=c;
	}
	out<<max_flow(1,n)<<"\n";
	return 0;
}