Cod sursa(job #1125569)

Utilizator h2g2Ford Prefect h2g2 Data 26 februarie 2014 18:28:40
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.75 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define nmax 100005
using namespace std;

queue <int> q;
vector <int> v[nmax];
int n, m, a, b, s, dist[nmax];
bool seen[nmax];

void bfs() {
	while(!q.empty()) {
		int x = q.front();
		q.pop();
		seen[x] = true;

		for(int i=0; i<v[x].size(); i++) {
			if(seen[v[x][i]]) continue;
			dist[v[x][i]] = dist[x] + 1;
			q.push(v[x][i]);
			seen[v[x][i]] = true;
		}
	}
}

int main() {
	ifstream f("bfs.in");
	ofstream g("bfs.out");

	f>>n>>m>>s;
	for(int i=1; i<=m; i++) {
		f>>a>>b;
		v[a].push_back(b);
	}

	q.push(s);
	bfs();

	for(int i=1; i<=n; i++) {
		if(i != s && dist[i] == 0) g<<"-1 ";
		else g<<dist[i]<<" ";
	}
	g<<"\n";

	return 0;
}