Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
type Queue struct {
	arr []int
}

func (q *Queue) push(v int) {
	q.arr = append(q.arr, v)
}

func (q *Queue) pop() int {
	res := q.arr[0]
	q.arr = q.arr[1:]
	return res
}

func (q *Queue) isEmpty() bool {
	return len(q.arr) == 0
}

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	G := make([][]int, N)
	for i := 0; i < N; i++ {
		u, k := sc.nextInt()-1, sc.nextInt()
		for j := 0; j < k; j++ {
			G[u] = append(G[u], sc.nextInt()-1)
		}
	}
	var q Queue
	seen := make([]int, N)
	for i := 0; i < N; i++ {
		seen[i] = -1
	}
	var search func(cur int)
	search = func(cur int) {
		for i := 0; i < len(G[cur]); i++ {
			next := G[cur][i]
			if seen[next] == -1 {
				q.push(next)
				seen[next] = seen[cur] + 1
			}
		}
	}
	q.push(0)
	seen[0] = 0
	for !q.isEmpty() {
		search(q.pop())
	}

	for i := 0; i < N; i++ {
		fmt.Fprintln(wtr, i+1, seen[i])
	}
	wtr.Flush()
}

C++: #include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
#define Graph vector<vector<int>>
using namespace std;

//そのまま再帰にかけて実行しては間に合わない。先に各部分木の根に対して、子に分配する数値を加算しておき、
//根である1から子に対して、根の数値を加算していく作業を一回だけ行えば条件は満たされる

void DFS(const Graph &G,int v,vector<bool> &seen,vector<int> &counter){//深さ優先探索。
//引数は順にグラフ、始点(注目点)、探索済みかどうか、各点の持つ値を記録するカウンタ
  
  seen[v]=true;

  for(auto next_v : G[v]){
    if(seen[next_v]) continue;
    counter[next_v]+=counter[v];
    DFS(G,next_v,seen,counter);
  }

  return ;

}

 
int main() {

  int N ;  cin >> N ;

  Graph G(N+1);//頂点はn個。今回は数値にそのまま対応させるために+1した

  rep(i,N){
    int u,k;
    cin >> u >> k;//頂点番号、頂点の数
    rep(j,k){
      int x; cin >> x;
      G[u].push_back(x);
    }
  }//入力終了

  vector<int> dist(N+1,-1);//全地点を未訪問で初期化
  
  dist[1]=0;//頂点1（スタート）の距離を0にする

  queue<int> que;//BFS用キュー

  que.push(1);

  while(!que.empty()){
    int v = que.front();
    que.pop();          //先頭頂点を取り出す
    
    for(int nv : G[v]){
      if(dist[nv]!=-1) continue;//探索済みならスルー

      //初めて候補に挙がった点は距離を入力し、キューに入れる
      dist[nv]= dist[v]+1;
      que.push(nv);
    }

  }

  for(int i=1;i<=N;i++){
    cout << i << ' ' << dist[i] <<endl ;
  }

  return 0;
}

C++: #include<iostream>
#include<vector>
#include<stack>
#include<cstdio>
using namespace std;
static const int MAX = 100000;
static const int NIL = -1;
int n ;
vector<int> G[MAX];
int color [MAX];
void dfs (int r,int c)
{
  stack <int> S;
  S.push(r);
  color[r] = c;
  while(!S.empty())
  {
    int u = S.top();
    S.pop();
    for(int i = 0;i<G[u].size();i++)
        {
          int v = G[u][i];
          if(color[v] == NIL)
          {
            color[v] = c;
            S.push(v);
          }
        }
  }
}
void ass()
{
  int id = 1;
  for(int i = 0;i<n;i++)
    color[i] = NIL;
  for(int u = 0;u<n;u++)
  {
    if(color[u] == NIL)
    dfs(u,id++);
  }
}
int main ()
{
  int s,t,m,q;
  cin>>n>>m;
  for(int i = 0;i<m;i++)
    {
      cin>>s>>t;
      G[s].push_back(t);
      G[t].push_back(s);
    }
  ass();
  cin>>q;
  for(int i = 0;i<q;i++)
  {
    cin>>s>>t;
    if(color[s] == color[t])
    {
      cout<<"yes"<<endl;
    }
    else cout<<"no"<<endl;
  }
  return 0 ;
}

C++: #include<iostream>
using namespace std;

typedef struct{
  int A[1000];
  int ans;
  bool c;
}node;
node T[1000];
int Q[100000000];
int head=0;
int tail=1;
int n;

void function(int num){
  while(true){
    if(head==tail)break;
    for(int i=2;i<=n;i++){
      if(T[num].A[i]==1){
	if(T[i].ans==0){
	  T[i].ans=T[num].ans+1;
	}
	Q[tail++]=i;
      }
    }
    //    cout<<"Q "<<Q[head]<<endl;
    num=Q[head++];
    //  cout<<head<<" "<<tail<<endl;
  }

}

int main(){
  int num;
  int son;
  int z;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>num;
    cin>>son;
    for(int j=0;j<son;j++){
      cin>>z;
      T[num].A[z]=1;
      }
  }
  Q[0]=1;
  function(1);
  T[1].ans=0;
  for(int i=2;i<=n;i++){
    if(T[i].ans==0){
      T[i].ans=-1;
    }
  }

  for(int i=1;i<=n;i++){
      cout<<i<<" "<<T[i].ans<<endl;
  }


  return 0;
}

C++: #include<iostream>
#include<vector>
#include<queue>

struct node {
	std::vector<int> child;
	int distance;
};

int main() {
	int node_num;

	std::cin >> node_num;

	std::vector<node> n(node_num);

	for (int i = 0; i < node_num; i++) {
		int num, to, node_val;
		std::cin >> node_val >> num;
		for (int j = 0; j < num; j++) {
			std::cin >> to;
			n[node_val - 1].child.push_back(to);
		}
		n[i].distance = -1;
	}

	//???????????????????????¢0
	n[0].distance = 0;
	std::queue<int> q;
	int dist = 1;
	q.push(1);
	while(q.size() != 0){
		int num = q.front();
		q.pop();
		for (std::vector<int>::iterator it = n[num - 1].child.begin(); it != n[num - 1].child.end(); it++) {
			if (n[*it - 1].distance > n[num - 1].distance + 1|| n[*it - 1].distance == -1) {
				n[*it - 1].distance = n[num - 1].distance + 1;
				q.push(*it);
			}
		}
	}

	for (int i = 0; i < node_num; i++) {
		std::cout << i + 1 << " " << n[i].distance << std::endl;
	}
	return 0;
}

C++: #include<iostream>
#include<vector>
#include<queue>
#include<map>
using namespace std;

int main() {
    int N;
    cin>>N;
    vector<vector<int> > graph(N);
    int u, k, tmp;
    for(int i=0;i<N;++i){
        cin>>u>>k;
        for(int j=0;j<k;++j){
            cin>>tmp;
            tmp--;
            graph[i].push_back(tmp);
        }
    }
    queue<int> que;
    queue<int> passque;
    que.push(0);
    passque.push(0);
    int node, pass;
    vector<int> ans(N);
    for(int i=0;i<N;++i){
        ans[i] = -1;
    }
    map<int, int> past;
    past[0]++;
    while(!que.empty()){
        node = que.front();que.pop();
        pass = passque.front();passque.pop();
        ans[node] = pass;
        for(int i=0;i<graph[node].size();++i){
            if(past[graph[node][i]]==0){
                que.push(graph[node][i]);
                passque.push(pass + 1);
            }
            past[graph[node][i]]++;
        }
    }
    for(int i=0;i<N;++i){
        cout<<i+1<<" "<<ans[i]<<endl;
    }
}