Submission #1090719

#	Time	Username	Problem	Language	Result	Execution time	Memory
1090719		kh0i	Papričice (COCI20_papricice)	C++17	110 / 110	136 ms	29264 KiB

papricice

#include "bits/stdc++.h"
using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...)
#endif

using ll = long long;
using pii = pair<int, int>;

#define F first
#define S second
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll get_rand(ll l, ll r) {
    assert(l <= r);
    return uniform_int_distribution<ll> (l, r)(rng);
}

const int N = 2e5 + 3;

int n, sz[N];
vector<int> g[N];

void dfs(int u, int pre = -1){
    sz[u] = 1;
    for(int v : g[u]){
        if(v == pre)
            continue;
        dfs(v, u);
        sz[u] += sz[v];
    }
}

int res = INT_MAX;
multiset<ll> out, anc;

void calc(int u, int pre = -1){
    auto it = out.lower_bound((n - sz[u]) / 2);
    if(it != out.end()){
        int x = *it, y = n - *it - sz[u];
        res = min(res, max({x, y, sz[u]}) - min({x, y, sz[u]}));
    }
    if(it != out.begin()){
        --it;
        int x = *it, y = n - *it - sz[u];
        res = min(res, max({x, y, sz[u]}) - min({x, y, sz[u]}));
    }

    it = anc.lower_bound((n + sz[u]) / 2);
    if(it != anc.end()){
        int x = *it - sz[u], y = n - *it;
        res = min(res, max({x, y, sz[u]}) - min({x, y, sz[u]}));
    }
    if(it != anc.begin()){
        --it;
        int x = *it - sz[u], y = n - *it;
        res = min(res, max({x, y, sz[u]}) - min({x, y, sz[u]}));
    }

    // debug(u, pre, out, anc, res);

    if(u != 1)
        anc.insert(sz[u]);

    for(int v : g[u]){
        if(v == pre)
            continue;
        calc(v, u);
    }

    if(u != 1){
        anc.erase(anc.find(sz[u]));
        out.insert(sz[u]);
    }
}

void solve(){
    cin >> n;
    for(int i = 1; i < n; ++i){
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    dfs(1);
    calc(1);

    cout << res;
}

int32_t main() {
    cin.tie(nullptr)->sync_with_stdio(0);
    #define task "troll"
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int test = 1;
//    cin >> test;
    for(int i = 1; i <= test; ++i){
//        cout << "Case #" << i << ": ";
        solve();
    }
    #ifdef LOCAL
        cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
    #endif
    return 0;
}

Compilation message (stderr)

papricice.cpp: In function 'int32_t main()':
papricice.cpp:101:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
papricice.cpp:102:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 60 / 60