#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <chrono>
#define pb push_back
#define INF 0x3f3f3f3f
#define LINF 0x3f3f3f3f3f3f3f3f
#define int long long
#define endl '\n'
#define ll long long
#define f first
#define fin cin
#define fout cout
#define s second
#define FAST cin.tie(0), cout.tie(0), ios::sync_with_stdio(0)
#define debug(x) cout << "DEBUG " << x << endl
#define debug2(x, y) cout << "DEBUG " << x << " " << y << endl
#define debug3(x, y, z) cout << "DEBUG " << x << " " << y << " " << z<< endl
#define debug4(x, y, z, o) cout << "DEBUG " << x << " " << y << " " << z<< " " << o << endl
#define all(x) x.begin(), x.end()
#define left vadia
#define lb lower_bound
#define right puta
using namespace std;
using namespace __gnu_pbds;
void setIO(string s) {
ios_base::sync_with_stdio(0); cin.tie(0);
freopen((s+".in").c_str(),"r",stdin);
freopen((s+".out").c_str( ),"w",stdout);
}
typedef pair<ll, ll> pii;
typedef vector<vector<char>> mat;
typedef pair<int, string> pis;
const ll mod = 1e9+7;
typedef vector<int> vi;
typedef pair<int, pair<int, int>> piii;
const int MAXN = 2e5 + 5;
int sz[MAXN], n, ans = INT_MAX;
vector<int> g[MAXN];
void get(int u, int p) {
sz[u] = 1;
for(int &i : g[u])
if(i != p) {
get(i, u);
sz[u] += sz[i];
}
}
int calc(int x, int y) {
int a1 = x, a2 = y - x, a3 = n - y;
return max({abs(a1 - a2), abs(a1 - a3), abs(a2 - a3)});
}
int calc2(int x, int y) {
int a1 = x, a2 = y, a3 = n - x - y;
return max({abs(a1 - a2), abs(a1 - a3), abs(a2 - a3)});
}
set<int> a, b;
void dfs(int u, int p) {
if(u != p) {
int ini = sz[u], mid, end = n, best = sz[u];
while(ini <= end) {
mid = (ini + end) >> 1;
if(calc(sz[u], mid) < calc(sz[u], mid + 1)) {
end = mid-1;
if(calc(sz[u], mid) < calc(sz[u], best))
best = mid;
}
else {
ini = mid + 2;
if(calc(sz[u], mid+1) < calc(sz[u], best))
best = mid+1;
}
}
auto it = a.lower_bound(best);
if(it != a.end())
ans = min(ans, calc(sz[u], *it));
if(it != a.begin()) {
it--;
ans = min(ans, calc(sz[u], *it));
}
it = a.lower_bound(best);
if(it != a.end()) {
it++;
if(it != a.end())
ans = min(ans, calc(sz[u], *it));
}
ini = 0, end = n, best = 0;
while(ini <= end) {
mid = (ini + end) >> 1;
if(calc2(sz[u], mid) < calc2(sz[u], mid + 1)) {
end = mid-1;
if(calc2(sz[u], mid) < calc2(sz[u], best))
best = mid;
}
else {
ini = mid + 2;
if(calc2(sz[u], mid+1) < calc2(sz[u], best))
best = mid+1;
}
}
auto it2 = b.lower_bound(best);
if(it2 != b.end())
ans = min(ans, calc2(sz[u], *it));
if(it2 != b.begin()) {
it2--;
ans = min(ans, calc2(sz[u], *it));
}
it2 = b.lower_bound(best);
if(it2 != b.end()) {
it2++;
if(it2 != b.end())
ans = min(ans, calc2(sz[u], *it));
}
}
a.insert(sz[u]);
for(int &i : g[u])
if(i != p)
dfs(i, u);
a.erase(sz[u]);
b.insert(sz[u]);
}
int32_t main() {
cin >> n;
for(int i = 0; i < n-1; i++) {
int a, b;
cin >> a >> b;
g[a].pb(b);
g[b].pb(a);
}
get(1, 1);
dfs(1, 1);
cout << ans << endl;
}
Compilation message
papricice.cpp: In function 'void setIO(std::string)':
papricice.cpp:27:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
27 | freopen((s+".in").c_str(),"r",stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
papricice.cpp:28:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
28 | freopen((s+".out").c_str( ),"w",stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
4 ms |
4972 KB |
Output is correct |
| 2 |
Correct |
4 ms |
4972 KB |
Output is correct |
| 3 |
Incorrect |
3 ms |
4972 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
4 ms |
4972 KB |
Output is correct |
| 2 |
Correct |
4 ms |
4972 KB |
Output is correct |
| 3 |
Incorrect |
3 ms |
4972 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
4 ms |
4972 KB |
Output is correct |
| 2 |
Correct |
4 ms |
4972 KB |
Output is correct |
| 3 |
Incorrect |
3 ms |
4972 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
