#include <bits/stdc++.h>
#include "stations.h"
using namespace std;
vector<int> a;
vector<vector<int>> g;
void dfs(int u, int p) {
a.push_back(u);
for (auto v : g[u]) {
if (v != p) {
dfs(v, u);
}
}
}
vector<int> label(int n, int k, vector<int> u, vector<int> v) {
g.assign(n, {});
for (int i = 0; i < n - 1; i++) {
g[u[i]].push_back(v[i]);
g[v[i]].push_back(u[i]);
}
int r = 0;
for (int i = 0; i < n; i++) {
if (g[i].size() > 2) {
r = i;
break;
}
}
vector<int> ret(n);
ret[r] = 0;
int cur = 1;
for (auto u : g[r]) {
int x = cur;
int p = r;
while (true) {
ret[u] = x;
x += g[r].size();
bool has = 0;
for (auto v : g[u]) {
if (v != p) {
has = 1;
p = u;
u = v;
break;
}
}
if (!has) break;
}
cur++;
}
return ret;
}
int find_next_station(int s, int t, vector<int> c) {
if (s == 0) {
int r = c.size();
for (auto x : c) {
if (t % r == x) {
return x;
}
}
}
int r = 0;
for (auto x : c) {
if (x != 0) {
r = abs(s - x);
}
}
if (r == 0) return 0;
if (s % r == t % r) {
if (s < t) {
return s + r;
} else {
return s - r;
}
} else {
for (auto x : c) {
if (x == s - r) {
return x;
}
}
return 0;
}
}
