Cod sursa(job #663613)

Utilizator avram_florinavram florin constantin avram_florin Data 18 ianuarie 2012 19:30:22
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.96 kb
#include<fstream>
#include<cstdio>
#include<vector>
#include<queue>

using namespace std;

const int MaxN = 100001;
const char InFile[] = "bfs.in";
const char OutFile[] = "bfs.out";

#define pb push_back

int n,m,S,cost[MaxN];
bool viz[MaxN];
vector<int> G[MaxN];
queue<int> Q;

void BFS()
{
	int nod;
	vector<int>::iterator it,iend;
	cost[S] = 0;
	Q.push(S);
	viz[S] = 1;
	while( !Q.empty() )
		{
			nod = Q.front();
			Q.pop();
			iend = G[nod].end();
			for( it = G[nod].begin() ; it != iend ; ++it )
				if( !viz[*it] )
					{
						viz[*it] = 1;
						cost[*it] = cost[nod] + 1;
						Q.push(*it);
					}
		}
}

int main()
{
	int i,x,y;
	ifstream fin( InFile );
	ofstream fout( OutFile );
	fin >> n >> m >> S;
	for( int i = 0 ; i < m ; i++ )
		{
			fin >> x >> y;
			G[x].pb(y);
		}
	for( i = 1 ; i <= n ; i++ )
		cost[i] = -1;
	BFS();
	for( i = 1 ; i <= n ; i++ )
		fout << cost[i] << ' ';
	fout << '\n';
	return 0;
}