Snakeless path

#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <set>
 
using namespace std;
 
void BFS(const vector<set<int>>& adj, vector<int>& distances){
    queue<int> q;
    q.push(0);
    distances[0] = 0;
 
    while(not q.empty()){
        int x = q.front();
        q.pop();
        //cout<<q.size()<<endl;
 
        for(unsigned long i=0;i<adj.size(); i++){
            if(adj[x].find(i) != adj[x].end())continue;
 
            if(distances[i]<0){
                distances[i]=distances[x]+1;
                q.push(i);
            }
        }
    }
}
 
void Gpath(const vector<set<int>>& adj, const vector<int>& distances, int ini, stack<int>& path){
 
    int x=ini;
    path.push(x);
 
    while (distances[x]!=0){
 
        for(unsigned long i=0;i<adj.size(); i++){
            //cout << "."<<endl;
            if(adj[x].find(i) != adj[x].end())continue;
 
            if(distances[i]!=-1 and distances[i]<distances[x]){
                path.push(i);
                x=i;
                break;
            }
        }
    }
}
 
 
int main(){
    int n,m;
    cin >> n >> m;
    vector<set<int>> adj(n);

 
    for(int i=0;i<n;i++)adj[i].insert(i); //[i]=false;
 
    for(int i=0;i<m;i++){
        int a,b;
        cin >> a >> b;
        adj[a-1].insert(b-1);
        adj[b-1].insert(a-1);
    }
 
    vector<int> distances(n,-1);
 
    BFS(adj, distances);
 
    //cout << "hola" << endl;
 
    if(distances[n-1]==-1){
        cout<<0<<endl;
        return 0;
    }
 
    stack<int> path;
 
    Gpath(adj,distances,n-1,path);
 
    //cout << "adeu" << endl;
 
    cout<<path.size()<<endl;
    while(not path.empty()){
        cout<<path.top()+1;
        if(path.top()!=n-1)cout<<" ";
        path.pop();
    }
    cout <<endl;
 
 
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: ACCEPTED

Test 44

Verdict: ACCEPTED

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: ACCEPTED

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED

Test 57

Verdict: ACCEPTED

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: ACCEPTED

Test 61

Verdict: ACCEPTED

Test 62

Verdict: ACCEPTED

Test 63

Verdict: ACCEPTED

Test 64

Verdict: ACCEPTED

Test 65

Verdict: ACCEPTED

Test 66

Verdict: ACCEPTED

Test 67

Verdict: ACCEPTED

Test 68

Verdict: ACCEPTED

Test 69

Verdict: ACCEPTED

Test 70

Verdict: TIME LIMIT EXCEEDED

Test 71

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Test 72

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Test 75

Verdict: ACCEPTED

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Verdict: ACCEPTED

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Verdict: ACCEPTED

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Test 85

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Test 86

Verdict: ACCEPTED

Test 87

Verdict: ACCEPTED

Test 88

Verdict: TIME LIMIT EXCEEDED

Test 89

Verdict: ACCEPTED