Cod sursa(job #860710)
#include <fstream>
#include <iostream>
#include <vector>
#include <queue>
using namespace std;
ifstream f ("bfs.in");
ofstream g ("bfs.out");
vector < vector <unsigned int> > graf;
vector <bool> visitat;
vector <int> drum;
int n, m, s;
void citire(){
f >> n >> m >> s;
graf.resize(n+1);
int x, y;
for(int i = 1; i <= m; ++i){
f >> x >> y;
graf[x].push_back(y);
}
f.close();
}
void afisare(){
for(int i = 1; i <= n; ++i){
if(drum[i] == 0 && i != s) g << -1 << " ";
else g << drum[i] << " ";
}
g.close();
}
void bfs(){
queue<unsigned int> coada;
vector<unsigned int>::iterator it;
visitat.resize(n+1);
drum.resize(n+1, 0);
visitat[s] = 1;
coada.push(s);
while(!coada.empty()){
for(it = graf[coada.front()].begin(); it != graf[coada.front()].end(); ++it ){
if(!visitat[*it]){
visitat[*it] = 1;
drum[*it] = drum[coada.front()] + 1;
coada.push(*it);
}
}
coada.pop();
}
}
int main(){
citire();
bfs();
afisare();
return 0;
}