oj.uz

답안 #871287

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
871287 2023-11-10T13:07:51 Z Onur_Ilgaz Papričice (COCI20_papricice) C++17
0 / 110
 2 ms 4956 KB 
#include <bits/stdc++.h>
#define fast cin.tie(0)->sync_with_stdio(0);
#define int long long
#define inf ((int)1e18)
#define N 200005
using namespace std;
vector <vector <int> > adj(N);
set <int> subt;
deque <int> dq;
int under[N];
int n, ans = inf;

void dfs0(int node, int ata) {
	under[node] = 1;
	for(auto it:adj[node]) {
		if(it == ata) continue;
		dfs0(it, node);
		under[node] += under[it];
	}
}

void dfs(int node, int ata) {
	int a = under[node];
	dq.push_front(a);
	auto index = subt.lower_bound((n - a) / 2); // >= ilk eleman
	// cout << node << ":\n";
	// for(auto it:dq) {
	// 	cout << it << " ";
	// }
	// cout << "\n";
	if(index != subt.end()) {
		int b = *(index);
		if(index != subt.begin()) index--;
		int c = n - b - a;
		int tans = max(abs(a - b), max(abs(a - c), abs(c - b)));
		ans = min(ans, tans);
	}
	if(index != subt.end()) {
		int b = *(index);
		int c = n - b - a;
		int tans = max(abs(a - b), max(abs(a - c), abs(c - b)));
		ans = min(ans, tans);
	}
	auto ind = lower_bound(dq.begin(), dq.end(), (n + a) / 2);
	if(ind != dq.end()) {
		// cout << *ind << " ";
		int b = *(ind) - a;
		if(ind != dq.begin()) ind--;
		int c = n - b - a;
		int tans = max(abs(a - b), max(abs(a - c), abs(c - b)));
		ans = min(ans, tans);
		// cout << a << " " << b << " " << c << "\n";
	}
	if(ind != dq.end()) {
		// cout << *ind << " ";
		int b = *(ind) - a;
		int c = n - b - a;
		int tans = max(abs(a - b), max(abs(a - c), abs(c - b)));
		ans = min(ans, tans);
		// cout << a << " " << b << " " << c << "\n";
	}
	for(auto it:adj[node]) {
		if(it == ata) continue;
		dfs(it, node);
	}
	subt.insert(under[node]);
	dq.pop_front();
}

int32_t main(){
	fast
	cin >> n;
	for(int i = 0; i < n - 1; i++) {
		int a, b;
		cin >> a >> b;
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	dfs0(1, 0);
	dfs(1, 0);
	cout << ans << "\n";
}

Subtask #1
0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 4956 KB Output is correct
2 Correct 2 ms 4956 KB Output is correct
3 Incorrect 2 ms 4956 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #2
0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 4956 KB Output is correct
2 Correct 2 ms 4956 KB Output is correct
3 Incorrect 2 ms 4956 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #3
0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 4956 KB Output is correct
2 Correct 2 ms 4956 KB Output is correct
3 Incorrect 2 ms 4956 KB Output isn't correct
4 Halted 0 ms 0 KB -