Shared code

#include<bits/stdc++.h>
using namespace std;
class MessageRoute{
private:
  int n;
  vector<vector<int>>graph;
  vector<int> prevNode;
public:
  MessageRoute(int n,vector<vector<int>>&graph){
    this->n=n;
    this->graph=graph;
    prevNode.resize(n+1,0);
  }
  vector<int> MinComputers(){
    queue<int>que;
    que.push(1);
    int node;
    prevNode[1]=-1;
    while(!que.empty()){
       node=que.front();
       que.pop();
       for(int connectedCompuer:graph[node]){
          if(prevNode[connectedCompuer]==0){
            prevNode[connectedCompuer]=node;
            que.push(connectedCompuer);
          }
       }
    }
    if(prevNode[n]==0){
      return {};
    }
    vector<int> computers;
    node=n;
    while(node!=-1){
      computers.push_back(node);
      node=prevNode[node];
    }
    reverse(computers.begin(),computers.end());
    return computers;
  }
};
int main(){
  int n,m,a,b;
  cin>>n>>m;
  vector<vector<int>>graph(n+1);
  for(int i=0;i<m;i++){
    cin>>a>>b;
    graph[a].push_back(b);
    graph[b].push_back(a);
  }
  MessageRoute route(n,graph);
  vector<int> computers=route.MinComputers();
  if(computers.size()==0){
    cout<<"IMPOSSIBLE"<<endl;
  }else{
    cout<<computers.size()<<endl;
    for(auto i:computers){
      cout<<i<<" ";
    }
  }
  return 0;
}