Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	nodes := make([]Node, n)

	for i := 0; i < n; i++ {
		nodes[i].list = make([]int, 0)
		nodes[i].d = -1
	}

	for i := 0; i < n; i++ {
		u := getNextInt(scanner)
		k := getNextInt(scanner)
		u--
		for ii := 0; ii < k; ii++ {
			v := getNextInt(scanner)
			v--
			nodes[u].list = append(nodes[u].list, v)
		}
	}

	queue := make([]int, n)
	queue[0] = 0
	nodes[0].d = 0
	d := 0
	i, j := 0, 1
	for i < j {
		d++
		prev := j
		for i < prev {
			for k, l := 0, len(nodes[queue[i]].list); k < l && i < n; k++ {
				if nodes[nodes[queue[i]].list[k]].d != -1 {
					continue
				}
				nodes[nodes[queue[i]].list[k]].d = d
				queue[j] = nodes[queue[i]].list[k]
				j++
			}
			i++
		}
	}

	for i := 0; i < n; i++ {
		fmt.Fprintln(writer, fmt.Sprintf("%d %d", i+1, nodes[i].d))
	}

	writer.Flush()
}

// Node ...
type Node struct {
	list []int
	d    int
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <math.h>
#include <map>
#include <functional>
#include <iomanip>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <typeinfo>
#define PI 3.14159265359
#define INF 99999999;
#define rep(i, n) for(int i=0; i<n; i++)
#define REP(n) rep(i, n)
#define EPS 1e-10
typedef long long ll;
using namespace std;
typedef pair<int, int> P;

double distanceAB(double xa, double ya, double xb, double yb);
//void trace(int A[], int N);

/*
class Target
{
public:
	vector <string> draw(int n)
	{

	}
};
*/


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

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

void bfs(int s)
{
	queue<int> q;
	q.push(s);
	REP(n) d[i] = INFTY;
	d[s] = 0;
	int u;
	while (!q.empty())
	{
		u = q.front(); q.pop();
		for (int v=0; v<n; v++)
		{
			if (M[u][v] == 0) continue;
			if (d[v] != INFTY) continue;
			d[v] = d[u] + 1;
			q.push(v);
		}
	}
	REP(n)
	{
		cout << i + 1 << " " << ((d[i] == INFTY) ? (-1) : d[i]) << endl;
	}
}


int main()
{
	int u, k, v;
	
	cin >> n;
	rep(i, n) rep(j, n) M[i][j] = 0;
	
	rep(i, n)
	{
		cin >> u >> k;
		u--;
		rep(j, k)
		{
			cin >> v;
			v--;
			M[u][v] = 1;
		}
	}
	
	bfs(0);
	
	return 0;
}


/*
void trace(int A[], int N)
{
	REP(N)
	{
		if (i > 0) cout << " ";
		cout << A[i];
	}
	cout << endl;
}
*/


double distanceAB(double xa, double ya, double xb, double yb)
{
	return sqrt((xb-xa)*(xb-xa) + (yb-ya)*(yb-ya));
}

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


//使用队列实现广度优先搜索

using namespace std;

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

/**
 * M 邻接矩阵
 * queue 记录下一个待访问顶点的队列
 * 将七点s到各顶点的最短距离记录在d[i]中
 */

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

void bfs(int s){
    queue<int> q;
    q.push(s);
    for(int i=0;i<n;i++){
        d[i]=INFTY;
    }
    d[s]=0;
    int u;
    while(!q.empty()){
        u=q.front(),q.pop();

        for(int v=0;v<n;v++){
            if(M[u][v]==0)
                continue;
            if(d[v]!=INFTY)
                continue;
            d[v]=d[u]+1;
            q.push(v);
        }
    }
    for(int i=0;i<n;i++){
        cout<<i+1<<" "<<(d[i]!=INFTY?d[i]:(-1))<<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;
        }
    }

    bfs(0);
    return 0;
}

C++: #include <iostream>
#include <queue>
#define INF 1000000
using namespace std;
class st
{
	public:
		int vertex;
		int dis;
	st();
	st(int,int);
};

st::st()
{
	vertex=-1;
	dis=-1;
}

st::st(int v,int d)
{
	vertex=v;
	dis=d;
}

int main()
{
	int n;
	cin>>n;
	int g[101][101];
	for(int i=0;i<=n;i++)
		for(int j=0;j<=n;j++)
		{
			if (i==j)
				g[i][j]=0;
			else
				g[i][j]=INF;
		}
	for(int i=0;i<n;i++)
	{
		int f,en;
		cin>>f>>en;
		for(int j=0;j<en;j++)
		{
			int t;
			cin>>t;
			g[f][t]=1;

		}
	}

/*	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
			cout<<g[i][j]<<" ";
		cout<<endl;
	}
*/
	int visited[101];
	for(int i=0;i<=n;i++)
		visited[i]=INF;

	queue<st> Q;
	st first=st(1,0);
	Q.push(first);
	while(!Q.empty())
	{
		st now=Q.front();
		Q.pop();
		for(int i=1;i<=n;i++)
		{
			if(g[now.vertex][i]+now.dis<visited[i])
			{
				visited[i]=g[now.vertex][i]+now.dis;
				Q.push(st(i,visited[i]));
			}
		}
	}
	
	for(int i=1;i<=n;i++)
		cout<<i<<" "<<(visited[i]>=INF?-1:visited[i])<<endl;
	return 0;
}

C++: #include<stdio.h>
 
 
int G[101][101], q1[101], q2[101], n;
 
void f(int a, int b){
  int i;
  q1[a] = b;
  for(i = 1; i <= B[a]; i++){
    if(b + 1 < q1[G[a][i]]) f(G[a][i], b + 1);
  }
}
 
int main(){
  int i, j, m;
 
  scanf("%d", &n);
 
  for(i = 1; i <= n; i++){
    q1[i] = 100000000;
    scanf("%d", &m);
    scanf("%d", &q2[m]);
 
    for(j = 1; j <= B[m]; j++) scanf("%d", &G[m][j]);
  }
 
  f(1, 0);
 
  for(i = 1; i <= n; i++){
    if(q1[i] == 100000000) q1[i] = -1;
  }
 
  for(i = 1; i <= n; i++) printf("%d %d\n", i, q1[i]);
 
  return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<string>
#include<queue>
#include<algorithm>

using namespace std;

queue<int> Q;
int N;
bool PATH[101][101];
int len[101];

void BFS(int id){
    Q.pop();
    for (int i = 1; i <= N; i++) {
        if (PATH[id][i]) {
            if (len[i] > len[id] + 1) {
                len[i] = len[id] + 1;
                Q.push(i);
            }
        }
    }
}

void BFS_m(){
    while (!Q.empty()) {
        BFS(Q.front());
    }
}

int main(){
    Q.push(1);
    cin >> N;
    for (int i = 1; i <= N; i++) {
        int bb;
        int n;
        cin >> bb;
        cin >> n;
        for (int k = 0; k < n; k++) {
            int s;
            cin >> s;
            PATH[i][s] = true;
        }
    }
    for (int i = 1; i <= N; i++) len[i] = 2000000000;
    len[1] = 0;
    
    BFS_m();
    
    for (int i = 1; i <= N; i++) {
        printf("%d %d\n",i,len[i]);
    }
    
    return 0;
}

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

struct edge{
    int node;
    edge *next;
}nodes[105];

int n,d[105],v[105];
queue<edge> E;

void bfs(){
    edge *e=E.front().next;
    while(e!=NULL){
        int num=e->node;
        if(v[num]==0){
            v[num]=1;
            d[num]=d[E.front().node]+1;
            E.push(nodes[num]);
        }
        e=e->next;
    }
    E.pop();
}

int main(){
    memset(v,0,sizeof(v));
    memset(d,0,sizeof(d));
    cin>>n;
    int i,j;
    for(i=1;i<=n;i++){
        int ii,n_i;
        cin>>ii>>n_i;
        nodes[ii].node=ii;
        edge *first=&nodes[ii];
        for(j=0;j<n_i;j++){
            edge *e=new edge();
            cin>>e->node;
            first->next=e;
            first=e;
        }
    }
    E.push(nodes[1]);
    while(E.size()!=0){
        bfs();
    }
    for(i=1;i<=n;i++)cout<<i<<" "<<d[i]<<endl;
    return 0;
}