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>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> P;
typedef pair<ll, ll> Pll;
#define debug(var)  do{std::cout << #var << " : ";view(var);}while(0)
template<typename T> void view(T e){std::cout << e << std::endl;}
template<typename T> void view(const std::vector<T>& v){for(const auto& e : v){ std::cout << e << " "; } std::cout << std::endl;}
template<typename T> void view(const std::vector<std::vector<T> >& vv){ for(const auto& v : vv){ view(v); } }
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

const int MOD = 1000000007;
const int INF = 1e9;

const int mod = 1000000007;
const int inf = 1e9;
#define PI acos(-1);
int dx[4] = {1,-1,0,0};
int dy[4] = {0,0,1,-1};
int ddx[8] = {1,1,1,-1,-1,-1,0,0};
int ddy[8] = {0,1,-1,0,1,-1,1,-1};

const int mxN = 103;
vector<int> adj[mxN];

int main(){
    int n;
    cin >> n;
    for(int i = 0; i < n; i++) {
        int v, k;
        cin >> v >> k;
        for(int j = 0; j < k; j++) {
            int a;
            cin >> a;
            a--;
            adj[i].push_back(a);
        }
    }

    vector<int> dis(n, INF);
    dis[0] = 0;
    queue<int> Q;
    Q.push(0);

    while(!Q.empty()) {
        int p = Q.front();
        Q.pop();

        for(auto e: adj[p]) {
            if(dis[e] == INF) {
                dis[e] = dis[p] + 1;
                Q.push(e);
            }
        }
    }

    for(int i = 0; i < n; i++) {
        cout << i+1 << " " << (dis[i]==INF?-1:dis[i]) << endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <queue>
using namespace std;
const int INF=1<<21;
const int maxn=100+10;
int n;
vector<int> g[maxn];
int vis[maxn];
int d[maxn];
void bfs(int s)
{
    queue<int> que;
    que.push(s);
    vis[s]=1;
    d[s]=0;
    while(!que.empty())
    {
        int u=que.front();que.pop();
        for(int i=0;i<g[u].size();i++)
        {
            int v=g[u][i];
            if(!vis[v])
            {
                que.push(v);
                d[v]=min(d[v],d[u]+1);

            }
        }
    }
}
int main()
{
//    freopen("in.txt","r",stdin);
    scanf("%d",&n);
    int no,cnt,dd;
    for(int i=0;i<n;i++)
    {
        scanf("%d%d",&no,&cnt);
        for(int j=0;j<cnt;j++)
        {
            scanf("%d",&dd);
            g[no-1].push_back(dd-1);
        }
    }
    for(int i=0;i<n;i++) d[i]=INF;
    bfs(0);
    for(int i=0;i<n;i++)
    {
        printf("%d %d\n",i+1,d[i]);
    }

    return 0;
}

C++: #include<iostream>
#include<queue>
#include<vector>
#define INF (int)1e9 + 7
using namespace std;
int n;
vector<pair<int, int> > adj[10000];
void dijkstra();
int main() {
    cin >> n;
    for (int i = 0; i < n; i++) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int v; //vertex cost
            cin >> v;
            adj[u].push_back(make_pair(1, v));
        }
    }
    dijkstra();
    return 0;
}
void dijkstra() {
    int dist[n + 1];
    dist[1] = 0;
    for (int i = 2; i <= n; i++) {
        dist[i] = INF;
    }
    priority_queue<pair<int, int> > q;
    q.push(make_pair(0, 1));
    while (!q.empty()) {
        int u = q.top().second;
        //int co = -q.top().first;
        q.pop();
        for (int i = 0; i < adj[u].size(); i++) {
            int v = adj[u][i].second; //adj[u]のi番目の番号
            int co2 = adj[u][i].first;
            if (dist[u] + co2 < dist[v]) {
                dist[v] = co2 + dist[u];
                q.push(make_pair(-dist[v] ,v));
            }
        }
    }
    for (int i = 1; i <= n; i++) {
        cout << i << " " << dist[i] << endl;
    }
    
}

C++: #include<iostream>
#include<cstdio>
#define INF 1<<30
#define MAX 100000
using namespace std;
  
class Queue{
private:
  int inf[MAX];
  int head,tail;
   
public:
   
  Queue(){
    syokika();
  }
   
  void syokika(){
    head = 0;
    tail = 0;
  }
   
  void push(int x){
    inf[tail]=x;
    if(MAX == tail+1)tail = 0;
    else tail++;
  }
   
  void pop(){
    if(MAX == head+1)head=0;
    else head++;
  }
   
  int front(){
    return inf[head];
  }
   
  bool empty(){
    if(tail - head == 0)return true;
    else return false;
  }
   
  int size(){
    return tail - head;
  }
   
};
  
int imap[200][200];
int k[200] = {0};
int ans[200] = {0};
bool used[200];
  
int main(){
  int n,u[1000];
  cin >> n;
  for(int i=0;i<200;i++)for(int j=0;j<200;j++)imap[j][i] = INF;
  
  for(int i=0;i<200;i++){
    k[i]=ans[i]=u[i]=-1;
  }
  
  for(int i=0;i<n;i++){
    cin >> u[i];
    cin >> k[u[i]];
    for(int j=0;j<k[u[i]];j++){
      cin >> imap[u[i]][j];
    }
  }
  
   int h;
  for(int i=0;i<n;i++){
    int Min = i;
    for(int j=i;j<n;j++){
      if(u[Min] > u[j])Min = j;
    }
    h = u[Min];
    u[Min] = u[i];
    u[i] = h;
  }
  
  Queue que = Queue();
  
  que.push(u[0]);
  ans[u[0]]=0;
  used[u[0]]=true;
  
  while(!que.empty()){
    int p = que.front(); que.pop();
    for(int i=0;i<k[p];i++){
      if(!used[imap[p][i]]){
    que.push(imap[p][i]);//cout << "push!= " << imap[p][i] << endl;
    used[imap[p][i]] = true;
    ans[imap[p][i]] = ans[p] + 1;
      }
    }
  }
  //for(int i=0;i<n;i++)cout << u[i] << endl;
   
  for(int i=0;i<n;i++){
    cout << u[i] << " " << ans[u[i]] << endl;
  }
  
  return 0;
}