Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	visitedAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		visitedAt: -1,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.visitedAt >= 0
}

func bfs(id vertexId, vqueue []vertexId, vertices []vertex) {
	vertex := &vertices[id-1]
	for _, vid := range vertex.adjs {
		if !vertices[vid-1].isVisited() {
			(&vertices[vid-1]).visitedAt = vertex.visitedAt+1
			vqueue = append(vqueue, vid)
		}
	}
	if len(vqueue) > 0 {
		nextId := vqueue[0]
		nextVqueue := vqueue[1:]
		bfs(nextId, nextVqueue, vertices)
	}
}

func solveBfs(vertices []vertex) {
	vertex := &vertices[0]
	vertex.visitedAt = 0
	vqueue := make([]vertexId, 0)
	bfs(vertex.id, vqueue, vertices)
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveBfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d\n", vertices[i].id, vertices[i].visitedAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

func nextInt(sc *bufio.Scanner) (int, error) {
	return strconv.Atoi(nextText(sc))
}

C++: #include <iostream>
#include <cstring>
#include <cstdlib>
#include <sstream>
#include <stack>
#include <queue>
#include <list>
#include <stdio.h>
#include <algorithm>
#define MAX 100000
using namespace std;
typedef long long ll;
int map[255][255];
int d[255];
bool vis[255];
void bfs(int cur,int n)
{
	queue<int> q;
	int u;
	q.push(cur);
	while(!q.empty())
	{
		u=q.front();q.pop();
		for(int i=1;i<=n;i++)
		{
			if(!map[u][i]) continue;
			if(d[i]>=0) continue;//不再重复计算或者入队 
			d[i]=d[u]+1;
			q.push(i);
		}
	}
	for(int i=1;i<=n;i++)
	{
		cout<<i<<" "<<d[i]<<endl;
	}
}
int main()
{	
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
		{
			map[i][j]=0;
		}
	for(int i=0;i<n;i++)
	{
		int cur,k,u;
		cin>>cur>>k;
		while(k--)
		{
			cin>>u;
			map[cur][u]=1;
		}
	}
	for(int i=2;i<=n;i++)
	{
		d[i]=-1;
	}
	d[1]=0;
	bfs(1,n);
	return 0;
}

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

using namespace std;

const int INF = 100000000;

int main(){
	int n;
	cin >> n;
	vector<vector<int>> node(n+1);
	for(int i=0;i<n;i++){
		int u,k,tmp;
		cin >> u >> k;
		for(int j=0;j<k;j++){
			cin >> tmp;
			node[u].push_back(tmp);
		}
	}
	
	//search
	vector<int> res(n+1,INF);
	queue<int> que;
	queue<int> copied;
	queue<int> zeros;
	que.push(1);
	
	int count = 0;
	for(int i=0;i<n-1;i++){
		while(que.size()){
			int k = que.front(); que.pop();
			//cout << "-> " << k << endl;
			if(res[k] >= INF) res[k] = count;
			for(int v:node[k]){
				copied.push(v);
			}
		}
		count++;
		que = copied;
		copied = zeros;
	}

	//output
	for(int i=1;i<=n;i++){
		cout << i << " " << res[i] << endl;
	}

	return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <complex>
#include <stack>
#include <queue>
#include <list>
#include <utility>
#include <set>
using namespace std;

int main(){
    int n;
    cin >> n;
    int g[110][110];
    int i, j;
    int u, k, v;
    int p;
    int dist[110];
    bool visited[110];
    
    for(i = 0; i < n; i++){
        for(j = 0; j < n; j++){
            g[i][j] = 0;
        }
    }
    
    for(i = 0; i < n; i++){
        dist[i] = -1;
        visited[i] = false;
    }
    
    for(i = 0; i < n; i++){
        cin >> u >> k;
        u--;
        for(j = 0; j < k; j++){
            cin >> v;
            v--;
            g[u][v] = 1;
        }
    }
    
    queue<int> q1, q2;
    q1.push(0);
    
    for(i = 0; q1.size(); i++){
        while(!q1.empty()){
            p = q1.front();
            q1.pop();
            
            if(visited[p]) continue;
            visited[p] = true;
            
            dist[p] = i;
            
            for(j = 0; j < n; j++){
                if(g[p][j]){
                    q2.push(j);
                }
            }
        }
        q1 = q2;
        while(!q2.empty()){
            q2.pop();
        }
    }
    
    for(i = 0; i < n; i++){
        printf("%d %d\n", i+1, dist[i]);
    }
}

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

int n, u, k, v, dp[101];
bool li[101][101];


int main(){
	fill(dp, dp + 101, -1);
	for (int i = 0; i < 101; i++) {
		fill(li[i], li[i] + 101, false);
	}
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		for (int j = 0; j < k; j++) {
			cin >> v;
			li[u][v] = li[v][u] = true;
		}
	}
	vector<int> l = vector<int>(1, 1);
	vector<int> l2 = vector<int>();
	dp[1] = 0;
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j < l.size(); j++) {
			for (int k = 1; k <= n; k++) {
				if (li[l[j]][k] && dp[k] < 0) {
					dp[k] = i;
					l2.push_back(k);
				}
			}
		}
		l2.swap(l);
		l2.swap(vector<int>());
	}
	for (int i = 1; i <= n; i++) {
		cout << i << " " << dp[i] << endl;
	}

	return 0;
}

C++: #include <iostream>

using namespace std;

#define N_MAX 100

int Adj[N_MAX][N_MAX] = {};
int Min_d[N_MAX];

void bfs(int v, int d, int num_node);

int main()
{
    int n, i, u, k, v, j;

    cin >> n;

    for (i = 0; i < n; i++) Min_d[i] = -1;

    //??£??\???????????????
    for (i = 0; i < n; i++) {
        cin >> u >> k;
        while (k-- > 0) {
            cin >> v;
            Adj[u-1][v-1] = 1;
        }
    }
/*
    cout << "show Adjacency matrix" << endl;
    for (i = 0; i < n; i++) {
        for (j = 0; j < n ; j++) {
            if (j == n - 1)
                cout << Adj[i][j] << endl;
            else
                cout << Adj[i][j] << ' ';
        }
    }
*/
    //??¢?´¢??????
    Min_d[0] = 0;
    bfs(1, 1, n);

    //????????????
    for(i = 1; i <= n; i++) {
        cout << i << ' ' << Min_d[i-1] << endl;
    }

    return 0;
}

void bfs(int v, int d, int num_node) {
    int i;
//    cout << "bfs node : " << v << endl;

    for(i = 1; i <= num_node; i++) {
        if (Adj[v-1][i-1] == 1) {
            if (Min_d[i-1] == -1 || Min_d[i-1] > d)
                Min_d[i-1] = d;
            bfs(i, d+1, num_node);
        }
    }
}

C++: #include <cstdio>
#include <vector>
#include <queue>
using namespace std;
int n, d[101]; vector<int> v[101];
void bfs(int c, int x) {
  queue<int> q; q.push(c);
  d[c] = x;
  while(!q.empty()) {
    int t = q.front(); q.pop();
    for(int i = 0; i < v[t].size(); ++i) {
      if(d[v[t][i]] > -1) continue;
      q.push(v[t][i]);
      d[v[t][i]] = d[t]+1;
    }
  }
}
int main() {
  scanf("%d", &n);
  for(int i = 0, u, k; i < n; ++i) {
    scanf("%d %d", &u, &k);
    for(int j = 0, vj; j < k; ++j) {
      scanf("%d", &vj);
      v[u].push_back(vj);
    }
    d[i+1] = -1;
  }
  bfs(1, 0);
  for(int id = 1; id <= n; ++id) {
    printf("%d %d\n", id, d[id]);
  }
}