#ifndef _DEBUG
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#endif
#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#ifndef _DEBUG
#include "stations.h"
#endif
#ifdef _DEBUG
std::vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v);
int find_next_station(int s, int t, std::vector<int> c);
#endif
vector<int> l;
int timer;
vector<vector<int>> adj;
void dfs(int i, int p)
{
if (p == -1 || l[p] == -1)
l[i] = timer++;
for (int c : adj[i])
if (c != p)
dfs(c, i);
if (l[i] == -1)
l[i] = timer++;
}
vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v)
{
timer = 0;
l.assign(n, -1);
adj.assign(n, {});
for (int i = 0; i < n - 1; i++)
{
adj[u[i]].push_back(v[i]);
adj[v[i]].push_back(u[i]);
}
dfs(0, -1);
return l;
}
int find_next_station(int s, int t, std::vector<int> c)
{
if (s > c.back())
{ // is larger than all adjacent
reverse(c.begin(), c.end());
if (t > s)
return c.back();
for (int other : c)
{
if (t >= other)
return other;
}
return c.back();
}
else
{ // is smaller than all adjacent
if (t < s)
return c.back(); // is not in subtree, as s is the smallest in the subtree
for (int other : c)
{
if (t <= other)
return other;
}
return c.back();
}
}
#ifdef _DEBUG
static int max_label = 0;
static int r, n, k, q;
static std::vector<int> u, v, labels, answers;
static std::map<int, int> reverse_labels;
static std::vector<std::vector<int>> adjlist;
static int s, t, w;
static std::vector<int> c;
int main()
{
assert(scanf("%d", &r) == 1);
for (int tc = 0; tc < r; tc++)
{
assert(scanf("%d%d", &n, &k) == 2);
u.resize(n - 1);
v.resize(n - 1);
adjlist.clear();
adjlist.resize(n);
for (int i = 0; i < n - 1; i++)
{
assert(scanf("%d%d", &u[i], &v[i]) == 2);
adjlist[u[i]].push_back(v[i]);
adjlist[v[i]].push_back(u[i]);
}
labels = label(n, k, u, v);
if ((int)labels.size() != n)
{
printf("Number of labels not equal to %d\n", n);
exit(0);
}
reverse_labels.clear();
for (int i = 0; i < n; i++)
{
if (labels[i] < 0 || labels[i] > k)
{
printf("Label not in range 0 to %d\n", k);
exit(0);
}
if (reverse_labels.find(labels[i]) != reverse_labels.end())
{
printf("Labels not unique\n");
exit(0);
}
reverse_labels[labels[i]] = i;
if (labels[i] > max_label)
{
max_label = labels[i];
}
}
assert(scanf("%d", &q) == 1);
for (int i = 0; i < q; i++)
{
assert(scanf("%d%d%d", &s, &t, &w) == 3);
c.clear();
for (int v : adjlist[s])
{
c.push_back(labels[v]);
}
std::sort(c.begin(), c.end());
int answer = find_next_station(labels[s], labels[t], c);
if (!std::binary_search(c.begin(), c.end(), answer))
{
printf("Label %d returned by find_next_station not found in c\n", answer);
exit(0);
}
answers.push_back(reverse_labels[answer]);
}
}
printf("%d\n", max_label);
for (int index : answers)
{
printf("%d\n", index);
}
exit(0);
}
#endif
