Snakeless path

#include <iostream>
#include <vector>
#include <queue>
#include <stack>
 
using namespace std;
 
void BFS(const vector<vector<bool>>& map, 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<map[x].size(); i++){
            if(!map[x][i])continue;
 
            if(distances[i]<0){
                distances[i]=distances[x]+1;
                q.push(i);
            }
        }
    }
}
 
void Gpath(const vector<vector<bool>>& map, 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<map[x].size(); i++){
            //cout << "."<<endl;
            if(!map[x][i])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<vector<bool>> adj(n,vector<bool>(n,true));
 
    for(int i=0;i<n;i++)adj[i][i]=false;
 
    for(int i=0;i<m;i++){
        int a,b;
        cin >> a >> b;
        adj[a-1][b-1]=false;
        adj[b-1][a-1]=false;
    }
 
    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: RUNTIME ERROR

Test 71

Verdict: RUNTIME ERROR

Test 72

Verdict: RUNTIME ERROR

Test 73

Verdict: RUNTIME ERROR

Test 74

Verdict: RUNTIME ERROR

Test 75

Verdict: RUNTIME ERROR

Test 76

Verdict: RUNTIME ERROR

Test 77

Verdict: RUNTIME ERROR

Test 78

Verdict: RUNTIME ERROR

Test 79

Verdict: RUNTIME ERROR

Test 80

Verdict: RUNTIME ERROR

Test 81

Verdict: RUNTIME ERROR

Test 82

Verdict: RUNTIME ERROR

Test 83

Verdict: RUNTIME ERROR

Test 84

Verdict: RUNTIME ERROR

Test 85

Verdict: RUNTIME ERROR

Test 86

Verdict: RUNTIME ERROR

Test 87

Verdict: RUNTIME ERROR

Test 88

Verdict: RUNTIME ERROR

Test 89

Verdict: RUNTIME ERROR