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- #include <iostream>
- #include <vector>
- #include <map>
- #include <cstring>
- using namespace std;
- typedef long long ll;
- const int maxn = 2e5 + 10;
- vector<int> graph[maxn];
- int subtree[maxn];
- int n, m;
- void subtree_size(int node, int prev) {
- subtree[node] = 1;
- for(int neighbour : graph[node]) {
- if(neighbour != prev) {
- subtree_size(neighbour, node);
- subtree[node] += subtree[neighbour];
- }
- }
- }
- int centroid(int node, int prev) {
- for(int neighbour : graph[node]) {
- if(neighbour != prev) {
- if(subtree[neighbour] * 2 > n) {
- return centroid(neighbour, node);
- }
- }
- }
- return node;
- }
- int main() {
- ios_base::sync_with_stdio(false);
- cin >> n;
- for(int i = 0; i < n - 1; i++) {
- int a, b;
- cin >> a >> b;
- a--; b--;
- graph[a].push_back(b);
- graph[b].push_back(a);
- }
- subtree_size(0, -1);
- cout << centroid(0, -1) + 1 << endl;
- return 0;
- }
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