Cod sursa(job #757533)

Utilizator lucian666Vasilut Lucian lucian666 Data 12 iunie 2012 16:37:04
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.35 kb



using namespace std;
#include<fstream>
#include<vector>
#include<cstring>
#include<queue>

#define NN 1001
#define pb push_back
ofstream out("maxflow.out");

vector<int>G[NN];
queue<int>Q;
typedef vector<int>::iterator IT;

int fl[NN][NN],cap[NN][NN],n,m,t[NN],ans,uz[NN];

void read();
int BFS();
void solve();

int main()
{
	read();
	solve();
	out<<ans;
	return 0;
}


void read()
{
	ifstream in("maxflow.in");
	in>>n>>m;
	for(int x,y,c;m;--m)
	{
		in>>x>>y>>c;
		cap[x][y]=c;
		G[x].pb(y);
		G[y].pb(x);
	}
}


int BFS()
{
	memset(uz,0,sizeof(uz));
	//queue<int>Q;
	Q.push(1);
	uz[1]=1;
	int k;
	while(!Q.empty())
	{
		k=Q.front();
		if(k!=n)
			for(IT I=G[k].begin();I!=G[k].end();++I)
				if(!uz[*I]&&fl[k][*I]<cap[k][*I])
					{
						uz[*I]=1;
						t[*I]=k;
						Q.push(*I);
				}
				Q.pop();
	}
	return uz[n];
}


void solve()
{
	int sol;
	while(BFS())
	{
		for(int i=1;i<n;i++)
			if(t[i]&&fl[i][n]<cap[i][n])
			{
				 sol=cap[i][n]-fl[i][n];
					for(int j=i;j!=1;j=t[j])
						if(cap[t[j]][j]-fl[t[j]][j]<sol)
							sol=cap[t[j]][j]-fl[t[j]][j];
						if(sol)
						{
							fl[i][n]+=sol;
							fl[n][i]-=sol;
									for(int j=i;j!=1;j=t[j])
										{
											fl[t[j]][j]+=sol;
											fl[j][t[j]]-=sol;
									}
									ans+=sol;
						}
			}
	}
}