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 <bits/stdc++.h>

using namespace std;

const int N = 100;
bool G[N][N];
int n;
vector<int> d(N, -1);

void bfs(int r) {
    queue<int> q;
    q.push(r);
    while (!q.empty()) {
        int u = q.front();
        q.pop();
        for (int v = 0; v < n; ++v) {
            if (G[u][v] && d[v] == -1) {
                d[v] = d[u] + 1;
                q.push(v);
            }
        }
    }
}

int main() {
    scanf("%d", &n);

    for (int i = 0; i < n; ++i) {
        int u, k;
        scanf("%d %d", &u, &k);
        --u;
        for (int j = 0; j < k; ++j) {
            int v;
            scanf("%d", &v);
            --v;
            G[u][v] = true;
        }
    }
    d[0] = 0;
    bfs(0);
    for (int u = 0; u < n; ++u) {
        cout << u + 1 << " " << d[u] << endl;
    }
}

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

int BFS(int s, int t, const vector<vector<int> >& G){
    vector<int> stock1;
    vector<int> stock2;
    vector<int> *s1p = &stock1;
    vector<int> *s2p = &stock2;
    stock1.push_back(s);
    int d = 0;
    while (1) {
        for (int i = 0; i < s1p->size(); i++) {
            if ((*s1p)[i] == t) return d;
            for (int j = 0; j < G[(*s1p)[i]].size(); j++) {
                s2p->push_back(G[(*s1p)[i]][j]);
            }
        }
        if (s1p == &stock1) {
            s1p = &stock2;
            s2p = &stock1;
        } else {
            s1p = &stock1;
            s2p = &stock2;
        }
        d++;
    }
}

int main(){
    int n;
    cin >> n;
    vector<vector<int> > G(n + 1);
    for (int i = 0; i < n; i++) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            G[u].push_back(v);
        }
    }
    for (int i = 1; i <= n; i++) {
        cout << i << " " << BFS(1, i, G) << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <queue>
#define MAX 101
#define NIL -1

using namespace std;


int matrix[MAX][MAX] = {0};
int dis[MAX];
//提交时须对time改名 
int n;


void bfs_visit(int u);
int next(int u);

int main()
{
	cin >> n;
	
	for (int i = 0; i < n; i++)
	{
		int u, k, v;
		cin >> u >> k;
		for (int j = 0; j < k; j++)
		{
			cin >> v;
			matrix[u][v] = 1;			
		}
	}
	
//显示邻接矩阵 
//	for (int i = 0; i < n; i++)
//	{
//		for (int j = 0; j < n; j++)
//		{
//			if(j) cout << ' ';
//			cout << matrix[i+1][j+1];		
//		}
//		cout << endl;
//	}

	bfs_visit(1);

	for (int i = 1; i <= n; i++)
	{
		cout << i << ' ';
		cout << dis[i] << endl;
	}
}



void bfs_visit(int u)
{
	
	//dis[]初始化，取值NIL时表示未访问 
	for (int i = 1; i <= n; i++)
		dis[i] = NIL;	
	dis[u] = 0;	
	
	queue<int> Q;
	Q.push(u);
	
//	int d = 1;
//	while (!Q.empty())
//	{
//		u = next(Q.front());
//
//		if (u)
//		{
//			dis[u] = d; 
//			Q.push(u);
//		}
//		else
//		{
//			Q.pop();			
//		}
//		
//		//判断是否进入下一层 
//		if (dis[Q.front()] == d) d++;
//
//	}

//另一种实现 
	while (!Q.empty())
	{
		u = Q.front();
		Q.pop();
		for (int v = 1; v <= n; v++)
		{
			if (matrix[u][v] != 0 && dis[v] == NIL)
			{
				dis[v] = dis[u] + 1;
				Q.push(v);
			}
		}
	} 
}


int next(int u)
{
	for (int i = 1; i <= n; i++)
	{
		if (matrix[u][i] != 0 && dis[i] == NIL)
			return i;
	}
	return 0;
}

C++: #include <iostream>
#include <queue>
using namespace std;
static const int N=100,INFTY=(1<<21);

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)?(-1):d[i])<<endl;
  }
}
int main() {
  int u,v,k,i,j;
  cin>>n;
  for (i=0; i<n; i++) {
    for (j=0; j<n; j++) {
      M[i][j]=0;
    }
  }
  for (i=0; i<n; i++) {
    cin>>u>>k;
    u--;
    for (j=0; j<k; j++) {
      cin>>v;
      v--;
      M[u][v]=1;
    }
  }
  bfs(0);
  return 0;
}