Company Queries II

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

typedef long long ll;


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

    ll a,b;
    ll array[n+1];
    ll adj[n+1];
    for(ll i = 0; i<n-1; i++) {
        cin >> a;
        array[i+2] = array[a]+1;
        adj[i+2] = a;
    }
    adj[1] = 1;

    ll ancestor[n+1][n] = {0};

    for(ll x = 1; x<=n; x++) {
        ll k = 1;
        while(k<n) {
            if(k == 1) {
                ancestor[x][k] = adj[x];
            } else {
                ancestor[x][k] = ancestor[ancestor[x][k/2]][k/2];
            }
            k *= 2;
        }
    }


    ll outputs[q];
    ll ances_pairs[n+1][n+1] = {0};
    for(ll i = 0; i<q; i++) {
        cin >> a >> b;
        ll k = 0;
        if(array[a] != array[b]) {
            if(array[a] < array[b]) swap(a,b);
            k = array[a] - array[b];
        }

        vector<ll> bin;
        while(k > 0) {
            bin.push_back(k % 2);
            k = k / 2;
        }

        for(long unsigned int j = 0; j<bin.size(); j++) {
            if(bin[j] != 0) {
                a = ancestor[a][(ll)pow(2,j)];
            }
            
        }


        ll p_a = a;
        ll p_b = b;
        while(a != b) {
            if(ances_pairs[a][b] != 0) {
                //cout << "pair";
                b = ances_pairs[a][b];
                break;
            }
            a = ancestor[a][1];
            b = ancestor[b][1];
        }
        outputs[i] = b;
        ances_pairs[p_a][p_b] = b;
        
    }

    for(ll i = 0; i<q; i++) {
        cout << outputs[i] << endl;
    }

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: RUNTIME ERROR

Test 7

Verdict: RUNTIME ERROR

Test 8

Verdict: RUNTIME ERROR

Test 9

Verdict: RUNTIME ERROR

Test 10

Verdict: RUNTIME ERROR

Test 11

Verdict: ACCEPTED

Test 12

Verdict: RUNTIME ERROR