Cod sursa(job #320205)

Utilizator blasterzMircea Dima blasterz Data 3 iunie 2009 23:40:40
Problema Flux maxim Scor 70
Compilator cpp Status done
Runda Arhiva educationala Marime 1.44 kb
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <fstream>
#define N 1001
#include <vector>

using namespace std;

int a[N][N];
int n;

#define oo 0x3f3f3f3f
#define pb push_back

typedef vector<int> vi;
typedef vector<int>::iterator vit;

vi A[N];


void read_file(char* buff_file)
{
	int m;
	ifstream f(buff_file);
	f>>n;
	f>>m;
	int left,right,value;
	int i;
	for (i=1;i<=m;++i)
	{
		f>>left>>right>>value;
		a[left][right]=value;
		A[left].pb(right);
		A[right].pb(left);
	}
}

int tata[N];
int v[N];
int nr;
bool used[N];



int bfs(int i=1)
{
	
	for (vit j=A[v[i]].begin(); j != A[v[i]].end(); ++j)
		if (a[v[i]][*j]!=0 && used[*j]==0)
		{
			tata[*j]=v[i];
			v[++nr]=*j;
			used[*j]=1;
			if (*j==n)
				return 1;
		}
	if (i<nr)
		bfs(i+1);
	else
		return 0;
}

void init()
{
	memset(used,0,sizeof(bool)*(n+1));
	used[1]=1;
	memset(v,0,sizeof(int)*(n+1));
	v[1]=1;
	nr=1;
	int i;
	for (i=1;i<=n;++i)
		tata[i]=1;
	tata[1]=0;
}

int max_flow()
{
	int flux=0;
	int min;
	int i;
	init();
	while (bfs(1))
	{
		//cout<<"1"; 
		min=oo;
		for (i=n;i!=1;i=tata[i])
		{
			if (min > a[tata[i]][i])
				min=a[tata[i]][i];
		}

		for (i=n;i!=1;i=tata[i])
		{
			a[tata[i]][i]-=min;
			a[i][tata[i]]+=min;
		}
		init();
		flux+=min;
	}
	return flux;
}

int main()
{
	read_file("maxflow.in");
	ofstream g("maxflow.out");
	g<<max_flow()<<"\n";
	return 0;
}