Go: package main

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

func main() {
	scn := bufio.NewScanner(os.Stdin)
	scn.Split(bufio.ScanWords)
	nextInt := func() int { scn.Scan(); r, _ := strconv.Atoi(scn.Text()); return r }
	w := bufio.NewWriter(os.Stdout)

	n := nextInt()
	vecs := make([][]int, n)
	for i := 0; i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			vecs[u-1] = append(vecs[u-1], nextInt()-1)
		}
	}

	ds := make([]int, 0, n)
	for i := 0; i < n; i++ {
		ds = append(ds, -1)
	}

	q := make([]int, 0, n)
	q = append(q, 0)
	ds[0] = 0

	for len(q) > 0 {
		i := pop(&q)
		for _, v := range vecs[i] {
			if ds[v] == -1 {
				ds[v] = ds[i]+1
				q = append(q, v)
			}
		}
	}

	for i, d := range ds {
		fmt.Fprintln(w, i+1, d)
	}

	w.Flush()
}

func pop(q *[]int) int {
	v := (*q)[0]
	*q = (*q)[1:]
	return v
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <stack>
#include <algorithm>
#include <iostream>
#include <string>
#include <map>
#include <queue>
#include <stdio.h>
#include <math.h>


using namespace std;

typedef long long ll;

typedef vector<vector<int>> vvi;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<ll> vll;

typedef pair<int, int> P;

typedef queue<int> qi;
typedef queue<string> qs;


#define rep(i, n) for(int i=0; i<(n); ++i)
#define repp(i, a, b) for(int i = (a); i <= (b); i++)
#define Rep(i, n) for(int i=n; i >= 0; i--)

#define all(v) v.begin(), v.end()
//sort( all(v) )　などと使える

int main() {
	int n; cin >> n;
	vector<vector<int>> G(n);
	rep(i, n) {
		int u, k; cin >> u >> k;
		u--;
		//G[u].resize(k);

		rep(j, k) {
			int v; cin >> v;
			v--;
			G[u].push_back(v);
		}
	}

	vector<int> dist(n, -1);

	dist[0] = 0;
	queue<int> que;
	que.push(0);

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

		for (auto nv : G[v]) {
			if (dist[nv] != -1) continue;
			else {
				dist[nv] = dist[v] + 1;
				que.push(nv);
			}
		}
	}

	rep(i, n) {
		cout << i + 1 << " " << dist[i] << endl;
	}

	//return 0;
}

C++: #include <cstdio>

void search(int (*A)[101], int *dis, int *found, int n){
    int hoge;
    int time=0;
    for(int k=1;k<n;k++){
        hoge = 1;
        for(int i=1;i<=n;i++){
            if(dis[i]==time){
                for(int j=1;j<=n;j++){
                    if(A[i][j]&&found[j]==0){
                        found[j]=1;
                        dis[j]=time+1;
                        hoge=0;
                    }
                }
            }
        }
        time++;
        if(hoge)return;
    }
}

int main(){
    int i, j, n, u, k, v;
    scanf("%d",&n);
    int found[n+1];
    int dis[n+1];
    dis[1]=0;
    found[1]=1;
    for(i=2;i<=n;i++){
        dis[i]=-1;
        found[i]=0;
    }
    int A[101][101];
    for(i=1;i<=n;i++){
        for(j=1;j<=n;j++){
            A[i][j]=0;
        }
    }
    for(i=1;i<=n;i++){
        scanf("%d %d",&u,&k);
        for(j=0;j<k;j++){
            scanf("%d",&v);
            A[u][v]=1;
        }
    }
    search(A,dis,found,n);
    for(i=1;i<=n;i++)printf("%d %d\n",i,dis[i]);
    return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <queue>
#define N 110
#define INF 0x3f3f3f3f
using namespace std;
//stack<int> s;
int n;
int m[N][N];
int used[N];
int d[N];
void bfs(int root){
    queue<int>q;
    while(!q.empty()) q.pop();
    q.push(root);
    d[root] = 0;
    while(!q.empty()){
        int u = q.front();
        used[u] = 1;
        q.pop();
        for(int i = 1; i <= n; i++){
            if(used[i] == 0 && m[u][i]){
                q.push(i);
                d[i] = d[u] + 1;
                used[i] = 1;
            }
        }
    }
}
int main(){
    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++) used[i] = 0;
    for(int i = 0; i < N; i++) d[i] = INF;
    scanf("%d", &n);
    for(int p = 0; p < n; p++){
        int node, k;
        scanf("%d %d", &node, &k);
        for(int i = 0; i < k; i++){
            int b;
            scanf("%d", &b);
            m[node][b] = 1;
        }
    }
    bfs(1);
    //for(int i = 1; i <= n; i++) if(used[i] == 0) bfs(i);
    for(int i = 1; i <= n; i++){
        printf("%d %d\n", i, d[i] == INF ? -1 : d[i]);
    }
    return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<cassert>
#include<cstdio>
#include<queue>

using namespace std;

int N, G[100][100], V[100], D[100];//G:２頂点,V:次数,D:距離

void bfs(int src){
	queue<int> Q;
	Q.push(src);
	fill(D, D + N, -1);
	D[src] = 0;
	while (!Q.empty()){
		int cur = Q.front();
		Q.pop();
		for (int k = 0; k < N; k++){
			if (G[cur][k] == 1 && D[k] == -1){
				D[k] = D[cur] + 1;
				Q.push(k);
			}
		}
	}
	for (int l = 0; l < N; l++){
		cerr << l + 1 << " " << D[l] << endl;
	}
}

int main(){
	scanf_s("%d", &N);
	int id, c;
	for (int i = 0; i < N; i++){
		scanf_s("%d", &id); id--;//配列は0から始まるので、頂点番号を-1して考える。
		scanf_s("%d", V + id);
		for (int j = 0; j < V[id]; j++){
			scanf_s("%d", &c); c--;//配列は0から始まるので、頂点番号を-1して考える。
			G[id][c] = 1;
		}
	}//データの読み込み完了。
	bfs(0);
}

C++: #include <bits/stdc++.h>
using namespace std;
#ifdef ENABLE_DEBUG_OUTPUT
#define DEBUG_LOG(s) cout << s << endl;
#else
#define DEBUG_LOG(s) void();
#endif

void bfs(const int start, vector<vector<int>>& graph,
         vector<int>& dist) {
    queue<int> q; q.push(start); dist[start] = 0;
    while(not q.empty()) {
        auto p = q.front(); q.pop();

        for (auto elm : graph[p]) {
            if(dist[elm] < 0 or dist[elm] > dist[p] + 1) {
                dist[elm] = dist[p] + 1;
                q.push(elm);
            }
        }
    }
}

int main(){
    int n;
    cin >> n;

    vector<vector<int>> g(n, vector<int>(0));
    for (auto i = 0; i < n; i++) {
        int u, k; cin >> u >> k; u--;
        for (auto j = 0; j < k; j++) {
            int v; cin >> v; v--;
            g[u].push_back(v);
        }
    }

    vector<int> dist(n, -1);
    bfs(0, g, dist);

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

C++: #include <iostream>
#include <queue>
 
using namespace std;
 
int D[110]={0};
void bfs(int src,int n,int g[110][110]){
 
queue<int> Q;
Q.push(src);
D[src]=0;
while (! Q.empty()){
    int cur =Q.front();
    Q.pop();
    for(int r=0;r<n;r++){
        if (g[cur][r]==1&&D[r]==0){
            D[r]=D[cur]+1;
            Q.push(r);
        }
    }
}
}
int main() {
int n,g[110][110]={0};
cin>>n;
int j,num,t;
for(int k=0;k<n;k++){
cin>>j>>num;
for(int kk=0;kk<num;kk++){
    cin>>t;
    g[k][t-1]=1;
}
}
bfs(0,n,g);

for(int a=0;a<n;a++){
    if(D[a]!=0){
    cout<<a+1<<" "<<D[a]<<endl;
}
else{
	if (a!=0){
    cout<<a+1<<" -1"<<endl;
}
	else{
		cout<<a+1<<" 0"<<endl;
	}
}
}
    return 0;
}

C++: #include<iostream>
#include<queue>
using namespace std;
const int maxn=110;
int table[maxn][maxn];
int d[maxn],vis[maxn];
int n;

void bfs(){
    queue<int> q;
    q.push(1);
    d[1]=0;
    vis[1]=1;
    while(!q.empty()){
        int v=q.front();
        q.pop();
        for(int i=1;i<=n;i++){
            if(!vis[i] && table[v][i]){
                vis[i]=1;
                d[i]=d[v]+1;
                q.push(i);
            }
        }
    }
}
int main(){
    int u,k,num;
    cin>>n;
    for(int i=1;i<=n;i++){
        d[i]=-1;
        vis[i]=0;
        cin>>u>>k;
        while(k--){
            cin>>num;
            table[u][num]=1;
        }
    }
    bfs();
    for(int i=1;i<=n;i++)
        cout<<i<<" "<<d[i]<<endl;

}