#include<bits/stdc++.h>
#define all(s) s.begin(),s.end()
#define F first
#define S second
using namespace std;
typedef int ll;
ll n,x,y,dp[20][200009],sz[200009],ans=1e9;
vector<vector<ll> >v;
multiset<ll>s;
void dfs(ll d,ll p)
{
dp[0][d]=p;
sz[d]=1;
for(auto&z:v[d])
if(z!=p)
{
dfs(z,d);
sz[d]+=sz[z];
}
s.insert(sz[d]);
}
void go(ll d,ll p)
{
auto u=s.find(sz[d]);
s.erase(u);
for(auto&z:v[d])
if(z!=p)
{
go(z,d);
}
if(d==1)
return;
ll o=n-sz[d];
o+=(o&1);
o/=2;
auto uu=s.lower_bound(o);
if(uu!=s.end())
{
x=max({sz[d],*uu,n-sz[d]-*uu});
y=min({sz[d],*uu,n-sz[d]-*uu});
ans=min(ans,x-y);
}
if(uu!=s.begin())
{
uu--;
x=max({sz[d],*uu,n-sz[d]-*uu});
y=min({sz[d],*uu,n-sz[d]-*uu});
ans=min(ans,x-y);
}
ll pp=d;
for(ll j=19; j>=0; j--)
if(sz[dp[j][pp]]-sz[d]<o)
pp=dp[j][pp];
if(pp!=d)
{
x=max({sz[d],sz[pp]-sz[d],n-sz[p]});
y=min({sz[d],sz[pp]-sz[d],n-sz[p]});
ans=min(ans,x-y);
}
if(pp!=1)
{
pp=dp[0][pp];
x=max({sz[d],sz[pp]-sz[d],n-sz[p]});
y=min({sz[d],sz[pp]-sz[d],n-sz[p]});
ans=min(ans,x-y);
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0),cout.tie(0);
cin>>n;
v.resize(n+1);
for(ll i=1; i<n; i++)
{
cin>>x>>y;
v[x].push_back(y);
v[y].push_back(x);
}
dfs(1,1);
for(ll j=1; j<20; j++)
for(ll i=1; i<=n; i++)
dp[j][i]=dp[j-1][dp[j-1][i]];
go(1,1);
cout<<ans;
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
460 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
460 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
460 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
460 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
460 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
460 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
