This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
// #include "stations.h"
using namespace std;
 
const int N = 1000;
int sz[N], pref[N];
vector<int> val, g[N];
 
void pre_dfs(int v, int p = -1){
    sz[v] = 1;
    for (int u : g[v]){
        if (u == p) continue;
        pre_dfs(u, v);
        sz[v] += sz[u];
    }
}
 
void dfs(int v, int p = -1){
    pref[v] = 0;
    for (int u : g[v]){
        if (u == p) continue;
        pref[v] += sz[u];
        val[u] = val[v] - sz[v] + pref[v];
        dfs(u, v);
    }
}
 
vector<int> label(int n, int k, vector<int> u, vector<int> v){
    for (int i = 0; i < n; i ++)
        pref[i] = sz[i] = 0, g[i].clear();
 
    val.resize(n, 0);
    for (int i = 0; i < n - 1; i ++){
        g[u[i]].push_back(v[i]);
        g[v[i]].push_back(u[i]);
    }
    pre_dfs(0);
    val[0] = sz[0];
    dfs(0);
 
    for (int i = 0; i < n; i ++)
        val[i]--;
 
    return val;
}
int find_next_station(int s, int t, vector<int> c){
    for (int x : c){
        if (x < s and t < s) return x;
        if (x > s and t > s) return x; 
    }
}
// int main(){
//     int t;
//     cin >> t;
//     while (t--){
//         int n, k;
//         cin >> n >> k;
//         vector<int> u(n - 1), v(n - 1);
 
//         for (int i = 0; i < n - 1; i ++)
//             cin >> u[i] >> v[i];
//         label(n, k, u, v);
//         for (int i = 0; i < n; i ++){
//             for (int j = 0; j < n; j ++){
//                 if (i == j) continue;
 
//                 vector<int> adj;
//                 for (int x : g[i])
//                     adj.push_back(val[x]);
//                 sort(adj.begin(), adj.end());
 
//                 int res = find_next_station(val[i], val[j], adj);
//                 // cout << val[i] << " -- " << val[j] << " == " << res << endl;
//                 cout << res << endl;
//             }
//         }
//     }
// }
Compilation message (stderr)
stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:52:1: warning: control reaches end of non-void function [-Wreturn-type]
   52 | }
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