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Cod sursa(job #882644)
#include <fstream>
#include<vector>
#include<fstream>
#include<queue>
using namespace std;
int m,n,x0,d[1000000],pred[1000000];
vector <int> a[1000000];
queue <int> q;
ifstream in("bfs.in");
ofstream out("bfs.out");
void citire()
{
int x,y;
in>>n>>m>>x0;
for (int i=1;i<=m;i++)
{
in>>x>>y;
a[x].push_back(y);
a[x].push_back(x);
}
}
void init()
{
for(int i=1;i<=n;i++)
d[i]=-1;
}
void bfs(int x0)
{
init();
int x,y;
q.push(x0);
d[x0]=0;
pred[x0]=0;
while(!q.empty())
{
x=q.front();
q.pop();
for(size_t i=0; i<a[x].size();i++)
{
y=a[x][i];
if(d[y]==-1)
{
q.push(y);
d[y]=1+d[x];
pred[y]=x;
}
}
}
}
int main()
{
citire();
bfs(x0);
for(int i=1;i<=n;i++)
if(d[i]==-1)
out<<"-1"<<" ";
else
out<<d[i]<<" ";
return 0;
}