oj.uz

답안 #495011

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
495011 2021-12-17T20:38:15 Z Victor Papričice (COCI20_papricice) C++17
0 / 110
 4 ms 4940 KB 
// #pragma GCC target ("avx,avx2,fma")
// #pragma GCC optimize ("Ofast,inline") // O1 - O2 - O3 - Os - Ofast
// #pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b - 1); i >= (a); --i)
#define trav(a, x) for (auto &a : x)

#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define debug(x) cout << #x << " = " << x << endl

#define umap unordered_map
#define uset unordered_set

typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;

typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;

const int INF = 1'000'000'007;

int n, ans = INF, sub_size[200001];
vi graph[200001];
set<int> cur, old;

void pre(int u, int p) {
    sub_size[u] = 1;
    trav(v, graph[u]) if (v != p) {
        pre(v, u);
        sub_size[u]+=sub_size[v];
    }
}

void dfs(int u, int p) {
    if (sz(cur)) {
        int p1 = sub_size[u];
        auto it = cur.lower_bound((n - sub_size[u]) / 2 + sub_size[u]);
        if (it == cur.end()) --it;

        rep(i, 0, 2) {
            int p2 = *it - sub_size[u], p3 = n - p1 - p2;
            int mn = min(p1, min(p2, p3)), mx = max(p1, max(p2, p3));
            ans = min(ans, mx - mn);
            if (it == cur.begin()) break;
            --it;
        }
    }

    if (sz(old)) {
        int p1 = sub_size[u];
        auto it = old.lower_bound((n - sub_size[u]) / 2);
        if (it == old.end()) --it;
        rep(i, 0, 2) {
            int p2 = *it - sub_size[u], p3 = n - p1 - p2;
            int mn = min(p1, min(p2, p3)), mx = max(p1, max(p2, p3));
            ans = min(ans, mx - mn);
            if (it == old.begin()) break;
            --it;
        }
    }

    if (u) cur.insert(sub_size[u]);
    trav(v, graph[u]) if (v != p) dfs(v, u);

    cur.erase(sub_size[u]);
    old.insert(sub_size[u]);
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    cin >> n;
    rep(i, 1, n) {
        int u, v;
        cin >> u >> v;
        graph[--u].pb(--v);
    }

    pre(0, 0);
    dfs(0, 0);
    cout << ans << endl;
    return 0;
}

Subtask #1
0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 4940 KB Output is correct
2 Correct 2 ms 4940 KB Output is correct
3 Incorrect 2 ms 4940 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #2
0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 4940 KB Output is correct
2 Correct 2 ms 4940 KB Output is correct
3 Incorrect 2 ms 4940 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #3
0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 4940 KB Output is correct
2 Correct 2 ms 4940 KB Output is correct
3 Incorrect 2 ms 4940 KB Output isn't correct
4 Halted 0 ms 0 KB -