Go: package main

import (
	"fmt"
	"os"
	"bufio"
	"strconv"
	"container/list"
)

const MaxNode int = 100

var d []int
var A [][]int
var N int
var l *list.List

func bfs(u int) {
	d[u] = 0
	l.PushBack(u)
	for ;l.Len() != 0; {
		u = l.Front().Value.(int)
		l.Remove(l.Front())
		for v:=0; v<N; v++ {
			if A[u][v] == 0 {
				continue
			}
			if d[v] != -1 {
				continue
			}
			d[v] = d[u] + 1
			l.PushBack(v)
		}
	}
}


func nextInt(scanner *bufio.Scanner) int {
	scanner.Scan()
	num, _ := strconv.Atoi(scanner.Text())
	return num
}

func print() {
	for i:=0; i<N; i++ {
		fmt.Printf("%d %d\n", i+1, d[i])
	}
}

func initVariable() {
	d = make([]int, MaxNode)
	A = make([][]int, MaxNode)
	l = list.New()
	for i:=0; i<MaxNode; i++ {
		A[i] = make([]int, MaxNode)
		d[i] = -1
	}
}


func main() {
	initVariable()
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	N = nextInt(scanner)
	for i:=0; i<N; i++ {
		idx := nextInt(scanner)
		cnt := nextInt(scanner)
		for j:=0; j<cnt; j++ {
			node := nextInt(scanner)
			A[idx-1][node-1] = 1 
		}
	}
	bfs(0)
	print()
}

C++: #include <bits/stdc++.h>
using namespace std;
static const int N=100,INFTY=(1<<21);
int n,M[N][N],d[N];
void bfs(int s){
    std::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(void){
    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);
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<(n); i++)
using ll = long long;
using P = pair<int, int>;
#include<queue>
static const int N = 100;
static const int INFTY = (1<<21);

int n, M[N][N];
int d[N]; // 距離で訪問状態（color）を管理する

void bfs(int s) {
    queue<int> q; // 標準ライブラリの queue を使用
    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 ,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++: //
// Created by 李青坪 on 2018/11/3.
//

#include <cstdio>
#include <algorithm>
#include <queue>

#define MAXN 101
using namespace std;
int n;
int graph[MAXN][MAXN];
int dist[MAXN];
bool visited[MAXN];
queue<int > q;

void init(){
    fill(dist, dist+MAXN, -1);
    fill(visited, visited+MAXN, false);
    dist[1] = 0;
}

void bfs(int i){
    for (int j = 1; j <= n; ++j) {
        if (graph[i][j] == 1){
            if (visited[j]) continue;
            q.push(j);
            visited[j] = true;
            dist[j] = dist[j] >= 0 ? min(dist[j], dist[i] + 1): dist[i] + 1;
        }
    }
    while (!q.empty()){
        int next = q.front();
        q.pop();
        bfs(next);
    }
}

int main(){
    scanf("%d", &n);
    int u, k;
    for (int i = 0; i < n; ++i) {
        scanf("%d %d", &u, &k);
        int node;
        for (int j = 0; j < k; ++j) {
            scanf("%d", &node);
            graph[u][node] = 1;
        }
    }
    init();
    bfs(1);
    for (int l = 1; l <= n; ++l) {
        printf("%d %d\n", l, dist[l]);
    }
}
/*
5
1 2 2 4
2 1 4
3 0
4 1 3
5 1 4
 */

C++: #include <bits/stdc++.h>
using namespace std;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

int n;
struct indata {
    int now; int dist;
};

int main() {
    cin >> n;
    vector< vector<int> > graph(n, vector<int>());
    for(int i = 0; i < n; ++i) {
        int u, k;
        cin >> u >> k;
        u--;
        for(int j = 0; j < k; ++j) {
            int v;
            cin >> v;
            v--;
            graph.at(u).push_back(v);
            // graph.at(v).push_back(u);
        }
    }
    
    indata first;
    first.now = 0; first.dist = 0;
    queue<indata> que;
    que.push(first);

    vector<bool> visited(n, false);
    vector<int> distgraph(n, 1e9);

    while(!que.empty()) {
        indata exeq = que.front();
        que.pop();
        visited.at(exeq.now) = true;
        chmin(distgraph.at(exeq.now), exeq.dist);
        for(int i = 0; i < graph.at(exeq.now).size(); ++i) {
            if(!visited.at(graph.at(exeq.now).at(i))) {
                indata next;
                next.now = graph.at(exeq.now).at(i);
                next.dist = exeq.dist + 1;
                que.push(next);
            }
        }
    }

    for(int i = 0; i < n; ++i) {
        if(distgraph.at(i) == 1e9) {
            cout << i+1 << " " << -1 << endl;
        }else {
            cout << i+1 << " " << distgraph.at(i) << endl;
        }
    }
}

C++: #include<iostream>
#include<queue>
using namespace std;
int N;
int D[101];
void bfs(int src){
    int u,k,a,d[101][101];
    bool visit[101];
    for(int i=1;i<=N;++i){
        cin>>u>>k;
        for(int j=0;j<k;++j){
            cin>>a;
            d[u][a]=1;
        }
        visit[i]=true;
    }
    queue<int>Q;
    Q.push(src);
    D[src]=0;
    visit[src]=false;
    while(!Q.empty()){
        int cur=Q.front();
        Q.pop();
        for(int i=1;i<=N;++i){
            if(d[cur][i]==1&&visit[i]){
                visit[cur]=false;
                visit[i]=false;
                D[i]=D[cur]+1;
                Q.push(i);
            }
        }
    }
    for(int i=1;i<=N;++i){
        if(i!=1&&D[i]==0){
            D[i]=-1;
        }
        cout<<i<<" "<<D[i]<<endl;
    }
}
int main(){
    cin>>N;
    int start=1;
    bfs(start);
}

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

int k[1000][1000], n, a, b, c, t, x[1000];
queue<int>Q;
queue<int>R;

int main() {
	memset(x, -1, sizeof(x));
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> a >> b;
		for (int j = 0; j < b; j++) {
			cin >> c;
			k[i][c] = 1;
		}
	}
	Q.push(1);
	x[1] = 0;
	while (!Q.empty()) {
		t++;
		while (!Q.empty()) {
			for (int i = 1; i <= n; i++) {
				if (x[i] == -1) {
					x[i] = t;
					R.push(i);
				}
			}
			Q.pop();
		}
		while (!R.empty()) {
			Q.push(R.front());
			R.pop();
		}
	}
	for (int i = 1; i <= n; i++) {
		cout << i << ' ' << x[i] << endl;
	}
	return 0;
}