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>
using namespace std;
#define int long long
#define endl "\n"
#define ff first
#define ss second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int N = 1e5 + 5;
int ans = 1e18,n;
vector<int> adj[N],sz(N);
multiset<int> other,anc;
void calc(int node,int p){
sz[node] = 1;
for(int go : adj[node]){
if(go == p) continue;
calc(go,node);
sz[node] = sz[go] + sz[node];
}
}
int search(multiset<int> &s,int x,int ty){
int res = 1e18,cur = x;
if(!ty) cur = (n - x) / 2 + x;
else cur = (n - x) / 2;
auto it = s.upper_bound(cur);
if(ty){
if(it != s.end()){
vector<int> tmp = {x,n - x - *it,*it};
sort(tmp.begin(), tmp.end());
res = min(res,tmp[2] - tmp[0]);
}
if(it != s.begin()){
vector<int> tmp = {x,n - *prev(it) - x,*prev(it)};
sort(tmp.begin(), tmp.end());
res = min(res,tmp[2] - tmp[0]);
}
return res;
}
if(it != s.end()){
vector<int> tmp = {x,n - *it,*it - x};
sort(tmp.begin(), tmp.end());
res = min(res,tmp[2] - tmp[0]);
}
if(it != s.begin()){
vector<int> tmp = {x,n - *prev(it),*prev(it) - x};
sort(tmp.begin(), tmp.end());
res = min(res,tmp[2] - tmp[0]);
}
return res;
}
void dfs(int node,int p){
ans = min({ans,search(anc,sz[node],0),search(other,sz[node],1)});
anc.insert(sz[node]);
for(int go : adj[node]){
if(go == p) continue;
dfs(go,node);
}
anc.erase(anc.find(sz[node]));
other.insert(sz[node]);
}
void solve(){
cin >> n;
for(int i = 1; i < n; i++){
int a,b; cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
calc(1,0);
dfs(1,0);
cout << ans << endl;
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
while(t--)
solve();
return 0;
}
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