Go: package main

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

type AdjacentList struct {
	matrix [][]int
}

func NewEmptyAdjacentList(dim int) *AdjacentList {
	matrix := make([][]int, dim)
	for i := 0; i < dim; i++ {
		matrix[i] = make([]int, dim)
	}
	return &AdjacentList{matrix: matrix}
}

func (al *AdjacentList) set(node int, adjacent int) {
	al.matrix[node-1][adjacent-1] = 1
}

func (al *AdjacentList) findAdjacentsFor(node int) []int {
	adjacents := []int{}
	for i, v := range al.matrix[node-1] {
		if v == 1 {
			adjacents = append(adjacents, i+1)
		}
	}
	return adjacents
}

type DistanceList struct {
	list []int
}

func NewDistanceList(dim int) *DistanceList {
	list := make([]int, dim)
	for i := 0; i < dim; i++ {
		list[i] = -1
	}
	return &DistanceList{list: list}
}

func (dl *DistanceList) set(node int, distance int) {
	dl.list[node-1] = distance
}

func (dl *DistanceList) get(node int) int {
	return dl.list[node-1]
}

func (dl *DistanceList) isVisited(node int) bool {
	return dl.list[node-1] >= 0
}

type Position struct {
	node     int
	distance int
}

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

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

	al := NewEmptyAdjacentList(dim)

	for i := 1; i <= dim; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}

		adjacentNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		for j := 0; j < adjacentNum; j++ {
			adjacent, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			al.set(node, adjacent)
		}
	}

	dl := NewDistanceList(dim)

	bfs(al, dl)

	for i := 1; i <= dim; i++ {
		fmt.Printf("%d %d\n", i, dl.get(i))
	}
}

func bfs(al *AdjacentList, dl *DistanceList) {
	stack := []Position{Position{node: 1, distance: 0}}
	for len(stack) > 0 {
		currentPosition := stack[0]
		stack = stack[1:]
		if !dl.isVisited(currentPosition.node) {
			dl.set(currentPosition.node, currentPosition.distance)
		}
		for _, v := range al.findAdjacentsFor(currentPosition.node) {
			if !dl.isVisited(v) {
				stack = append(stack, Position{node: v, distance: currentPosition.distance + 1})
			}
		}
	}
}

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

C++: #include <cstdio>
#include <cstring>
#include <vector>
#include <queue>
//original idea: stupid wanna check the node with many bfs search 
using namespace std;
#define N 105 // number of nodes
vector<int> neighbors[N]; //start from 1
queue<int> q;
//http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_11_C bfs
int dist[N];
int vis[N];
int res = 0;
void bfs(int d){
	if(q.empty()) return;
	//until q is empty
	while(!q.empty()){
		int temp = q.front();
		q.pop();
		if(dist[temp]!=-1){
			if(d<dist[temp]) dist[temp] = d;
			else {dist[temp] = dist[temp];}
		}else {
			dist[temp] = d;
		}
		for(int i = 0; i<neighbors[temp].size(); i++){
			d = dist[temp] +1;//next lever
		if(dist[neighbors[temp].at(i)] == -1){//not visited
			q.push(neighbors[temp].at(i));
			dist[neighbors[temp].at(i)] = d;
			}
		}
		
	}
	
}

int main()
{
    int n;
    scanf("%d",&n);
    memset(dist, -1, sizeof(dist));
    memset(vis, -1, sizeof(dist));
    for(int i = 0; i<n; i++){
        int node;
        scanf("%d",&node);
        int num;
        scanf("%d",&num);
        for(int j = 0; j<num; j++){
        	int temp;
        	scanf("%d",&temp);
        	neighbors[node].push_back(temp);
        	neighbors[temp].push_back(node);
		}
    }
	q.push(1);//begin from 1
    bfs(0);
    for(int i = 1; i<=n; i++){
    	printf("%d %d\n",i, dist[i]);
	}
    return 0;
}

C++: #include<iostream>
#include<queue>
#define INF 1000000
using namespace std;

 queue<int> q;
int a[101][101];
int d[101];
int n;

void bfs(int s){
  int t;
  for(int i=1;i<=n;i++)d[i]=INF;
  d[s]=0;
  while(!q.empty()){
    t=q.front(),q.pop();
    for(int i=1;i<=n;i++){
      if(d[i]!=INF || a[t][i]!=1) continue;
       q.push(i),d[i]=d[t]+1;
    }
  }
}

int main(){
  int top,m,s;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>top>>m;
    for(int j=0;j<m;j++)
      cin>>s,a[top][s]=1;
     } 
  q.push(1);
   bfs(1);
  for(int i=1;i<=n;i++) cout<<i<<" "<<d[i]<<endl;
    return 0;
}

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

using namespace std;

queue<int> que;

void bfs(vector<vector<int> > &G, int s, int *seen) {
    seen[s] = 0;
    que.push(s);
    
    while (!que.empty()) {
        int u = que.front();
        que.pop();

        for (int i = 0; i < G[u].size(); i++) {
            int v = G[u][i];

            if (seen[v] != -1)  
                continue;

            seen[v] = seen[u] + 1;
            que.push(v);
        }
    }
}

int main() {
    vector<vector<int> > G;
    int n;  cin >> n;
    G.resize(n);
    for (int i = 0; i < n; i++) {
        int u, k;   cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int x;  cin >> x;
            G[u-1].push_back(x-1);
        }
    }

    int *seen = new int[n];
    for (int i = 0; i < n; i++)
        seen[i] = -1;
    seen[0] = 0;

    bfs(G, 0, seen);

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

    return 0;
}

C++: #include<cstdio>
#include<queue>
using namespace std;
static const int INF=(1<<21);
static const int MAXN=101;
struct p{
	int d;
	int cnt;
};
int main()
{
	int n,m[MAXN][MAXN],i,j,u,k,v,l,t[MAXN];
	p e,f;
	queue<p> q;
	bool used[MAXN]={};
	scanf("%d",&n);
	for(i=1;i<n+1;i++){
		for(j=1;j<n+1;j++){
			m[i][j]=INF;
		}
	}
	for(i=0;i<n;i++){
		scanf("%d %d",&u,&k);
		for(j=0;j<k;j++){
			scanf("%d",&v);
			m[u][v]=1;
		}
	}
	used[1]=true;
	e.d=1;
	e.cnt=0;
	q.push(e);
	while(!q.empty()){
		e=q.front();
		q.pop();
		for(i=1;i<n+1;i++){
			if(m[e.d][i]==1&&used[i]==false){
				f.d=i;
				f.cnt=e.cnt+1;
				q.push(f);
				used[i]=true;
				t[i]=e.cnt+1;
			}
		}
	}
	for(i=1;i<n+1;i++){
		if(used[i]==true){
			printf("%d %d\n",i,t[i]);
		}
		else{
			printf("%d -1\n",i);
		}
	}
	return 0;
}

C++: #include<bits/stdc++.h>
#include<string>
#include<cctype>
#include<cmath>
#include<queue> 
#define rep(i,n) for(int i=0;i<(n);i++)
using namespace std;
 
int main(){
  queue <int> q1;
  int n,i,j;
  cin >> n;
  int d[n][n];
  int m[n];
  int v[n];
  rep(i,n){
    m[i]=10000;
    v[i]=0;
    rep(j,n){
      if(i==j){
        d[i][j]=0;
      }else{
        d[i][j]=10000;
      }
    }
  }
  m[0]=0;

  rep(i,n){
    int u,k;
    cin >> u >> k;
    if(k>0){
      rep(j,k){
        int v;
        cin >> v;
          d[u-1][v-1]=1;
      }
    }
  }   

  q1.push(0);
  while(!q1.empty()){
    int u = q1.front(); q1.pop();
      rep(j,n){
        if(d[u][j]==1 && v[j]==0){
          q1.push(j);
          m[j] = min(m[j],m[u]+1);
        }
      }
    v[u]=1;
  }

  rep(i,n){
    cout << i+1 << ' ';
    if(m[i]==10000){
      cout << -1 << endl;
    }else{
      cout << m[i] << endl;
    }
  }

  return 0;
}

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

using namespace std;

#define MAX 100
#define INF 1e9

int n;
int G[MAX][MAX];
int dist[MAX];

void bfs(){
  bool used[MAX];
  fill(dist,dist+n,INF);
  fill(used,used+n,false);
  dist[0] = 0;

  queue<int> Q;
  Q.push(0);

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

    for(int i = 0 ; i < n ; i++){
      if(!used[i] && G[v][i] != INF){
	used[i] = true;
	dist[i] = dist[v] + 1;
	Q.push(i);
      }
    }
  }
}

int main(){
  cin >> n;

  fill(G[0],G[MAX],INF);
  for(int i = 0 ; i < n ; i++){
    int u,k,v;
    cin >> u >> k;
    for(int j = 0 ; j < k ; j++){
      cin >> v;
      G[u-1][v-1] = 1;
    }
  }

  bfs();

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

  return 0;
}