Go: package main

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

const MAX = 1000
const NIL = -1

type Node struct {
	id    int
	depth int
}

type Queue struct {
	head      int
	tail      int
	container [MAX]Node
}

func (q *Queue) inQueue(x Node) {
	q.container[q.tail] = x
	q.tail = (q.tail + 1) % MAX
}

func (q *Queue) deQueue() Node {
	x := q.container[q.head]
	q.head = (q.head + 1) % MAX
	return x
}

func (q *Queue) isEmpty() bool {
	return q.head == q.tail
}

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

func main() {
	n := scanInt()
	route := make([][]int, n)
	for i := range route {
		u, k := scanInt(), scanInt()
		u--
		route[u] = make([]int, k)
		for j := range route[u] {
			num := scanInt()
			num--
			route[i][j] = num
		}
	}

	d := make([]int, n)
	for i := range d {
		d[i] = NIL
	}

	start := Node{0, 0}
	que := Queue{}
	que.inQueue(start)
	for !que.isEmpty() {
		node := que.deQueue()
		if d[node.id] != NIL {
			continue
		}
		d[node.id] = node.depth

		for _, nextId := range route[node.id] {
			next := Node{id: nextId, depth: node.depth + 1}
			que.inQueue(next)
		}
	}

	for i, depth := range d {
		fmt.Println(i+1, depth)
	}
}

C++: #include <bits/stdc++.h>
using namespace std;

typedef long long ll;


int d[200];
bool table[200][200];

void init(){
    for(int i=0;i<200;i++){
        d[i]=-1;
        for(int j=0;j<200;j++){
            table[i][j]=false;
        }
    }
}

void bfs(int itr, int dis, int n){
    d[itr] = dis;
    for(int i=0;i<n;i++){
        if(table[itr][i]&&(d[i]<0||d[i]>dis+1)){
            bfs(i, dis+1,n);
        }
    }
}

void solve(int n){
    bfs(0,0,n);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    init();
    int n;
    cin >> n;
    int u,k,v;
    for(int i=0;i<n;i++){
        cin >> u >> k;
        for(int j=0;j<k;j++){
            cin >> v;
            table[u-1][v-1]=true;
        }
    }

    solve(n);

    for(int i=0;i<n;i++){
        cout << i+1 << " " << d[i] << endl;
    }

    return 0;
}

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

int main() {
	int a[101][101] = {{0}};
	int u, k, v, km;
	km = 0;
	while ( cin >> u, k ) {
		for ( int i = 1; i <= k; i++ ) {
			cin >> v;
			a[u][v] = 1;
		}
		km++;
	}
	int n0;
	int b[km + 1] = {- 1};
	queue<int> q;
	q.push( 1 );
	b[1] = 0;
	int cou = 0;
	for ( int i = 1; i <= km; i++ ) {
		n0 = q.front();
		q.pop();
		cou++;
		for ( int j = 1; j <= km + 1; j++ ) {
			if ( a[n0][j] == 1 && b[j] == - 1 ) {
				q.push( j );
				b[j] = cou;
			}
			if ( q.empty ) break;
		}
	}
	for ( int i = 1; i <= km; i++ )
		cout << i << " " << b[i] << endl;
}

C++: #include <bits/stdc++.h>
using namespace std;
int N,mas[101][101],v[101],cnt=0,st[101];
queue<int> q;

void bfs(int u){
    v[u]++;
    //st[u]=cnt;
    q.push(u);
    while(!q.empty()){
        int n=q.front();
        q.pop();
        for(int i=1;i<N+1;i++){
            if(mas[n][i] && !v[i]){
                v[i]++;
                st[i]=st[n]+1;
                q.push(i);
            }
        }
    }
}

int main(void){
    // Your code here!
    int u,k,vx;
    cin>>N;
    
    for(int i=1;i<N+1;i++){
        cin>>u>>k;
        for(int j=1;j<k+1;j++){
            cin>>vx;
            mas[u][vx]++;
        }
    }
    
    bfs(1);
    for(int i=1;i<N+1;i++){
        if(i>1&& !st[i]) cout<<i<<" "<<"-1"<<endl;       
        else cout<<i<<" "<<st[i]<<endl;  
    } 
}

C++: #include <bits/stdc++.h>
using namespace std;

static const int N=100;
static const int INFTY=(1<<21);

int n,m[N][N];
int d[N];

void dfs(int a){
  queue<int> q;
  q.push(a);
  for(int i=0;i<n;i++) d[i]=INFTY;
  d[a]=0;
  int b;
  while(!q.empty()){
    b=q.front();
    q.pop();
    for(int j=0;j<n;j++){
      if(m[b][j]==0) continue;
      if(d[j]!=INFTY) continue;
      d[j]=d[b]+1;
      q.push(j);
    }
  }
  for(int i=0;i<n;i++) cout << i+1 << " " << ((d[i]==INFTY) ? (-1) : d[i]) << endl;
}

int main(){
  int u,k,v;

  cin >> n;
  for(int i=0;i<n;i++){
    for(int j=0;j<n;j++) m[i][j]=0;
  }

  for(int i=0;i<n;i++){
    cin >> u >> k;
    u--;
    for(int j=0;j<k;j++){
      cin >> v;
      v--;
      m[u][v]=1;
    }
  }
  dfs(0);
  return 0;
}

C++: #include<iostream>
#include<queue>
using namespace std;
#define N 100

int graph[N][N];
int dis[N];
int check[N];
int n;
queue<int> q;

void init(){
    cin>>n;
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            graph[i][j] = 0;  //图初始化
        }
        check[i]=0;           //标记数组初始化
        dis[i] = -1;
    }
    int v,count,x;
    for(int i=0;i<n;i++){
        cin>>v;
        cin>>count;
        for(int i=0;i<count;i++){
            cin>>x;
            graph[v-1][x-1]=1;
        }
    }
    q.push(1);
    check[0]=1;
    dis[0]= 0;
}

int BFS(int v){
    for(int i=0;i<n;i++){
        if(graph[v-1][i]>0&&check[i]==0){
            q.push(i+1);
            check[i]=1;
            dis[i] = dis[v-1]+1;
        }
    }
    q.pop();
}

int main(){
    init();
    while(q.size()>0){
        BFS(q.front());
    }
    for(int i=0;i<n;i++){
        cout<<i+1<<" "<<dis[i]<<endl;
    }
    return 0;
}

C++: #include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

#define rep(i,n)   for (int i = 0; i < (n); ++i)
#define sort(a)    sort((a).begin(), (a).end());
#define uniq(a)    SORT(a);(a).erase(unique((a).begin(), (a).end()), (a).end());
#define find(a,x)  find((a).begin(), (a).end(), (x)) != (a).end()
#define reverse(a) reverse((a).begin(), (a).end());
#define out(d) cout << (d);
#define outl(d) std::cout<<(d)<<"\n";
#define Yes() printf("Yes\n");
#define No() printf("No\n");
#define YES() printf("YES\n");
#define NO() printf("NO\n");
#define ceil(x, y) ((x + y - 1) / (y))

using namespace std;
using ll = long long;
using P = pair<ll,ll>;

const ll MOD = 1000000007; // 10^9 + 7

const int MAX_N = 100;
int d[MAX_N + 1];
int N;
vector<vector<int>> g(MAX_N + 1);

void bfs() {
  queue<P> q;
  q.push(make_pair(1, 0));

  while (!q.empty()) {
    P p = q.front(); q.pop();
    int node = p.first;
    int dist = p.second;

    if (d[node] >= 0) continue;

    d[node] = dist;
    for (int i = 0; i < g[node].size(); i++) {
      q.push(make_pair(g[node][i], dist + 1));
    }
  }
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  srand((unsigned)time(NULL));

  cin >> N;
  for (int i = 0; i < N; i++) {
    int u; cin >> u;
    int k; cin >> k;
    for (int ki = 0; ki < k; ki++) {
      int tmp; cin >> tmp;
      g[u].push_back(tmp);
    }
    sort(g[u])
  }
  memset(d, -1, sizeof(d));

  bfs();

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