题目：
代码：
#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#define maxn 11111
using namespace std;
vector<int> a[maxn];
int x,y,n,m,ans,dis[maxn];
bool visited[maxn];
int main()
{
cin>>n>>m;for(int i=1;i<=m;i++){
cin>>x>>y;a[x].push_back(y);a[y].push_back(x);}for(int i=1;i<=n;i++){
memset(visited,0,n+1);ans=0;queue<int> q;q.push(i);dis[i]=0;visited[i]=true;while (!q.empty()){
int now=q.front();q.pop();if (dis[now]<=6) ans++;if (dis[now]==6) continue;for (auto to:a[now]){
if (!visited[to]) {
q.push(to);visited[to]=true;dis[to]=dis[now]+1;}}}//ansprintf("%d: %.2lf%%\n",i,(double)ans/n*100);}return 0;
}