Cod sursa(job #904479)

Utilizator zig_zagFMI Alexandru Gabriel zig_zag Data 4 martie 2013 15:02:01
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.77 kb
#include <iostream>
#include <fstream>
#include <queue>
#include <vector>
using namespace std;

ifstream in("bfs.in"); ofstream out("bfs.out");
int n,m,s;

vector <int> v[100001];
vector <int> viz;
queue <int> q;

void read()
{
	int x,y,i;
	in >> n >> m >> s;
	viz.resize(n+1);
	for(i=1;i<=m;i++)
	{
		in >> x >> y;
		v[x].push_back(y);
	}
	for(i=1; i<=n; i++)
		viz[i]=-1;
}

void bfs()
{
	vector<int>::iterator it;
	while (!q.empty())
	{
		int vf=q.front();
		q.pop();
		for (it=v[vf].begin(); it!=v[vf].end(); it++)
		{
			if(viz[*it]==-1)
			{
				q.push(*it);
                viz[*it]=viz[vf]+1;
            }
        }
	}
}
int main()
{
	read();
	viz[s]=0;
	q.push(s);
	bfs();
	for(int i=1;i<=n;i++)
        out << viz[i] << ' ';
}