Distinct Routes

#include <bits/stdc++.h>
using namespace std;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, m;
    cin >> n >> m;
    
    if(n < 2){
        cout << "0";
        return 0;
    }
    
    vector<int> forbidden1;
    vector<int> forbiddenn;
    
    for(int i=0; i<m; i++){
        int a, b;
        cin >> a >> b;
        if(a == 1){
            forbidden1.push_back(b);
        }
        if(b == 1){
            forbidden1.push_back(a);
        }
        if(a == n){
            forbiddenn.push_back(b);
        }
        if(b == n){
            forbiddenn.push_back(a);
        }
    }
    
    sort(forbidden1.begin(), forbidden1.end());
    sort(forbiddenn.begin(), forbiddenn.end());
    
    bool found = false;
    int intermediate = -1;
    for(int k=2; k<=n-1; k++){
        bool forbidden_with_1 = binary_search(forbidden1.begin(), forbidden1.end(), k);
        if(forbidden_with_1){
            continue;
        }
        bool forbidden_with_n = binary_search(forbiddenn.begin(), forbiddenn.end(), k);
        if(forbidden_with_n){
            continue;
        }
        intermediate = k;
        found = true;
        break;
    }
    
    if(found){
        cout << "3\n1 " << intermediate << " " << n;
    }
    else{
        bool direct_forbidden = binary_search(forbidden1.begin(), forbidden1.end(), n);
        if(!direct_forbidden){
            cout << "2\n1 " << n;
            return 0;
        }

        cout << "0";
    }
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: ACCEPTED

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER