#include "stations.h"
#include <algorithm>
#include <vector>
#include <functional>
std::vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v) {
std::vector<int> labels(n, -1);
std::vector<std::vector<int> > a(n, std::vector<int>());
for(int i=0;i<n-1;++i)
a[u[i]].push_back(v[i]), a[v[i]].push_back(u[i]);
int ctr=0;
std::function<void(int,int,bool)> dfs=[&](int n, int p, bool t)
{
if(t) labels[n]=ctr++;
for(int x:a[n])
if(x!=p)
dfs(x, n, !t);
if(!t) labels[n]=ctr++;
};
dfs(0, -1, 0);
return labels;
}
int find_next_station(int s, int t, std::vector<int> c) {
if(s < c[0]) // all neighbors postorder
{
if(t<s) return c.back();
if(t>c.back()) return c.back();
return *std::lower_bound(c.begin(), c.end(), t);
}
else // all neighbors preorder
{
if(t>s) return c[0];
if(t<c[0]) return c[0];
return *std::prev(std::upper_bound(c.begin(), c.end(), t));
}
}
