Problem:
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Breadth First Search

Write a program which reads an directed graph $G = (V, E)$, and finds the shortest distance from vertex $1$ to each vertex (the number of edges in the shortest path). Vertices are identified by IDs $1, 2, ... n$.

Input

In the first line, an integer $n$ denoting the number of vertices, is given. In the next $n$ lines, adjacent lists of vertex $u$ are given in the following format:

$u$ $k$ $v_1$ $v_2$ ... $v_k$

$u$ is ID of the vertex and $k$ denotes its degree.$v_i$ are IDs of vertices adjacent to $u$.

Constraints

$1 \leq n \leq 100$

Output

For each vertex $u$, print $id$ and $d$ in a line. $id$ is ID of vertex $u$ and $d$ is the distance from vertex $1$ to vertex $u$. If there are no path from vertex $1$ to vertex $u$, print -1 as the shortest distance. Print in order of IDs.

Sample Input 1

4
1 2 2 4
2 1 4
3 0
4 1 3

Sample Output 1

1 0
2 1
3 2
4 1

Reference

Introduction to Algorithms, Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and Clifford Stein. The MIT Press.

Solution in C (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>
int n,i,j,u,k,tmp;
int list[100][100]={};
int lengthlist[100];

void search(int y,int length){
	int ii;
	length++;
	lengthlist[y]=length;


	for(ii=0;ii<n;ii++){
		if(list[y][ii]==1){
			if(lengthlist[ii]<=length&&lengthlist[ii]>=0){
				continue;
			}
			search(ii,length);
		}
	}
}

int main(void) {


	scanf("%d",&n);
	for(i=0;i<n;i++){
		scanf("%d",&u);
		scanf("%d",&k);
		for(j=0;j<k;j++){
			scanf("%d",&tmp);
			list[u-1][tmp-1]=1;
		}
	}
	for(i=0;i<n;i++){
	lengthlist[i]=-1;
	}
	search(0,-1);



	for(j=0;j<n;j++){
		printf("%d %d\n",j+1,lengthlist[j]);
	}

	return 0;
}