Cod sursa(job #519993)

Utilizator radubbRadu B radubb Data 7 ianuarie 2011 10:16:27
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.93 kb
#include <iostream>
#include <fstream>
#include <queue>
using namespace std;

#define nmax 100001
long n, m, s;
int viz[nmax];
queue <int> C;


struct nod
{
	int y;
	nod *prev; // previous
}*v[nmax];

void add(nod *&dest, long val)
{
	nod *p = new nod;
	p -> y = val;
	p -> prev = dest;
	dest = p;
}

void citire()
{
	long x, y;
	ifstream in("bfs.in"); in>>n>>m>>s;
	for(long i=1; i<=m; i++)
	{
		in>>x>>y;
		add(v[x], y);
	}
}


inline void afisare()
{
	long i;
	ofstream out("bfs.out");
	for(long i=1; i<=n; i++)
		if(!viz[i])
			if(i==s)
				out<<0<<" ";
			else
				out<<-1<<" ";
		else
			out<<viz[i]-1<<" ";
		
}

void bfs(int x)
{
	C.push(x); nod *p; viz[x] = 1;
	while(!C.empty())
	{
		x = C.front(); C.pop();
		for(p=v[x]; p; p=p->prev)
			if(!viz[p->y])
			{
				viz[p->y] = viz[x]+1;
				C.push(p->y);
			}
	}
}

int main()
{
	citire();
	bfs(s);
	afisare();
	return 0;
}