#include <bits/stdc++.h>
std::vector<std::vector<int>> adj;
int prev_max_idx = 0;
int send_message(int N, int i, int Pi) {
if (adj.empty()) {
adj.resize(N);
}
adj[i].push_back(Pi);
adj[Pi].push_back(i);
std::vector<int> d(N);
auto dfs = [&](auto &&self, int u, int p) -> void {
for (int &i : adj[u]) {
if (i != p) {
d[i] = d[u] + 1;
self(self, i, u);
}
}
};
dfs(dfs, 0, -1);
int it = std::max_element(d.begin(), d.end()) - d.begin();
if (d[it] > d[prev_max_idx]) {
prev_max_idx = it;
} else if (d[it] == d[prev_max_idx]) {
it = prev_max_idx;
}
if (i < N - 2) {
return 0;
}
if (i == it) {
return 101;
}
if (i == N - 2) {
return it % 100 + 1;
}
if (i == N - 1) {
return it / 100 + 1;
}
return -1; // we should never reach this
}
std::pair<int, int> longest_path(std::vector<int> S) {
const int n = S.size();
if (S[n - 1] == 101) {
return {0, n - 1};
}
if (S[n - 2] == 101) {
return {0, n - 2};
}
return {0, (S[n - 1] - 1) * 100 + S[n - 2] - 1};
}
