Longest route

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

typedef long long ll;

const ll N = 1000000;

vector<ll> adj[N];

ll value[N] = {0};

ll state[N] = {0};

bool dfs(ll s, ll parents[]) {
    if (state[s] == 1) return false;
    if (state[s] == 2) return true;
    state[s] = 1;
    for (auto u: adj[s]) {
        if(value[u]< value[s]+1) {
            value[u] = value[s]+1;
            parents[u] = s;
        }
        if(!dfs(u, parents)) return false;
    }
    state[s] = 2;
    //cout << "We push state = " << s << endl;
    return true;
}

int main() {
    ll n, m;
    cin >> n >> m;

    ll a,b;
    for(ll i = 0; i<m; i++) {
        cin >> a >> b;
        adj[a].push_back(b);
    }
    ll parents[n+1] = {0};
    for(ll s = 1; s <= n; s++) {
        if(state[s] != 2) {
            if(!dfs(s, parents)) {
                cout << "Cycle" << endl;
                return 0;
            }
        }
    }
    if(value[n] == 0) {
        cout << "IMPOSSIBLE";
        return 0;
    }
    cout << value[n]+1 << endl;
    a = n;
    while(a != 1) {
        cout << a<< " ";
        a = parents[a];
    }
    cout << 1 << " ";
    cout << endl;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: TIME LIMIT EXCEEDED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: TIME LIMIT EXCEEDED

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

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: ACCEPTED

Test 19

Verdict: WRONG ANSWER

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: WRONG ANSWER