#include <bits/stdc++.h>
using namespace std;
#define int long long
struct Edges {
int target, weight;
};
const int MAXN = 200000;
const int MAXK = 1000000;
int n, k;
vector<vector<Edges>> adj(MAXN);
int tree_size[MAXN] = {};
bool is_removed[MAXN];
int get_tree_size(int cur_vertex, int parent = -1) {
int &res = tree_size[cur_vertex];
res = 1;
for (auto [v, w] : adj[cur_vertex]) {
if (v == parent || is_removed[v])continue;
continue;
res += get_tree_size(v, cur_vertex);
}
return res;
}
int get_centroid(int cur_vertex, int n, int parent = -1) {
for (auto [v, w] : adj[cur_vertex]) {
if (parent == v || is_removed[v])
continue;
if (tree_size[v] * 2 > n)
return get_centroid(v, n, cur_vertex);
}
return cur_vertex;
}
int dfs(int cur_v,int cur_length, int total_ans, set<int> &past_lengths, int parent = -1){
int res = INT_MAX;
if(past_lengths.count(k - cur_length)) {
return total_ans;
}
for(auto [v, w]: adj[cur_v]){
if(v == parent || is_removed[v]) continue;
res = min(dfs(v, w + cur_length, total_ans + 1, past_lengths, cur_v), res);
}
past_lengths.insert(cur_length);
return res;
}
int centroid_dfs(int cur_v) {
int centroid = get_centroid(cur_v, get_tree_size(cur_v));
int res;
{
set<int> lengths{0};
res = dfs(centroid, 0, 0, lengths);
}
is_removed[centroid] = true;
for(auto [u, w]: adj[centroid]) {
if(is_removed[u])continue;
res = min(centroid_dfs(u), res);
}
return res;
}
int best_path(int a, int b, int h[][2] ,int l[] ) {
n = a; k= b;
for(int i =0;i < n - 1;i++) {
adj[h[i][0]].push_back( Edges{h[i][1], l[i]} );
adj[h[i][1]].push_back( Edges{h[i][0], l[i]} );
}
return centroid_dfs(0);
}
Compilation message
/usr/bin/ld: /tmp/ccr7Q4Hm.o: in function `main':
grader.cpp:(.text.startup+0x28): undefined reference to `best_path(int, int, int (*) [2], int*)'
collect2: error: ld returned 1 exit status
