Breadth first traversal for undirected graph

here we are assuming that all the nodes are connected


#include<stdio.h>
#include<vector>
#include<queue>
using namespace std;
void bfs(vector<int> ar[],int visited[],int i,int n){
  int j;
  queue<int> que;
  visited[i]=1;
  que.push(i);
  while(que.size()>0){
   i=que.front();
   que.pop();
   printf("%d\n",i);
   for(j=0;j<ar[i].size();j++){
          if(visited[ar[i][j]]==0){
              que.push(ar[i][j]);
              visited[ar[i][j]]=1;
          }
      }
  }

}
int main(){
  int a,b,i,j,n,m;
  printf("no of nodes\n");
  scanf("%d",&n);
  vector<int> ar[n+9];
  int visited[n+9];
  for(i=0;i<n+9;i++){
    visited[i]=0;
   }
   printf("no of edges\n");
   scanf("%d",&m);
   printf("Enter edges\n");
   for(j=0;j<m;j++){
     scanf("%d %d",&a,&b);
     ar[a].push_back(b);
     ar[b].push_back(a);
   }
   printf("from which node to traverse\n");
   scanf("%d",&i);
   bfs(ar,visited,i,n);
  return 0;
}