Company Queries II

#include <iostream>
#include <vector>
#include <algorithm>


struct Element {
    int boss;
    int level;
    std::vector<int> bosses = {};
};

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(NULL);
    int n, q;
    std::cin >> n >> q;
    std::vector<Element> elements(n + 1);
    elements[1] = Element{1, 1, {}};
    for (int i = 2; i <= n; i++) {
        std::cin >> elements[i].boss;
        elements[i].level = elements[elements[i].boss].level + 1;
        elements[i].bosses = elements[elements[i].boss].bosses;
        elements[i].bosses.push_back(elements[i].boss);
    }
    std::vector<std::pair<int, int>> queries(q);
    for (int j = 0; j<q; j++) {
        std::cin >> queries[j].first >> queries[j].second;
    }
    for (int j = 0; j<q; j++) {
        Element a = elements[queries[j].first];
        Element b = elements[queries[j].second];
        if (a.level < b.level) {
            int diff = b.level - a.level;
            for (int k = 0; (1 << k) <= diff; k++) {
                if (diff & (1 << k)) {
                    b = elements[b.bosses[k]];
                }
            }
        } else if (a.level > b.level) {
            int diff = a.level - b.level;
            for (int k = 0; (1 << k) <= diff; k++) {
                if (diff & (1 << k)) {
                    a = elements[a.bosses[k]];
                }
            }
        }
        if (a.boss == b.boss) {
            std::cout << a.boss << std::endl;
        } else {
            int max_log = a.bosses.size();
            for (int k = max_log - 1; k >= 0; k--) {
                if (a.bosses[k] != b.bosses[k]) {
                    a = elements[a.bosses[k]];
                    b = elements[b.bosses[k]];
                }
            }
            std::cout << a.boss << std::endl;
        }
    }
}

Test 1

Verdict: RUNTIME ERROR

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: RUNTIME ERROR

Test 7

Verdict: ACCEPTED

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: RUNTIME ERROR

Test 10

Verdict: RUNTIME ERROR

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: RUNTIME ERROR