Submission #482527

#	Time	Username	Problem	Language	Result	Execution time	Memory
482527		jalsol	Papričice (COCI20_papricice)	C++17	110 / 110	272 ms	33920 KiB

papricice

#ifdef LOCAL
#include "local.h"
#else
#include <bits/stdc++.h>
#define debug(...)
#define DB(...)
#endif

using namespace std;

using ll = long long;
using ld = long double;

#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()

#define For(i, l, r) for (int i = (l); i <= (r); ++i)
#define Ford(i, r, l) for (int i = (r); i >= (l); --i)
#define Rep(i, n) For (i, 0, (n) - 1)
#define Repd(i, n) Ford (i, (n) - 1, 0)
#define Fe(...) for (auto __VA_ARGS__)

template <class C> inline int isz(const C& c) { return static_cast<int>(c.size()); }
template <class T> inline bool chmin(T& a, const T& b) { return (a > b) ? a = b, true : false; }
template <class T> inline bool chmax(T& a, const T& b) { return (a < b) ? a = b, true : false; }

const bool __initialization = []() {
    cin.tie(nullptr)->sync_with_stdio(false);
#define TASK "empty"
    if (fopen(TASK".inp", "r")) {
        (void)(!freopen(TASK".inp", "r", stdin));
        (void)(!freopen(TASK".out", "w", stdout)); }
    cout << setprecision(12) << fixed;
    return true;
}();

constexpr ld eps = 1e-9;
constexpr int inf = 1e9;
constexpr ll linf = 1e18;

// =============================================================================

constexpr int maxn = 2e5 + 5;

int n;
vector<int> g[maxn];

int sz[maxn];

void DfsSize(int u, int p) {
    sz[u] = 1;

    Fe (v : g[u]) {
        if (v != p) {
            DfsSize(v, u);
            sz[u] += sz[v];
        }
    }
}

multiset<int> in, out;

vector<int> findClosest(const multiset<int>& st, int val) {
    vector<int> ret;
    auto it = st.upper_bound(val);

    if (it != st.end()) {
        ret.push_back(*it);
    }
    if (it != st.begin()) {
        ret.push_back(*(--it));
    }

    return ret;
}

int findDiff(int a, int b, int c) {
    array<int, 3> temp = { a, b, c };
    sort(all(temp));
    return temp[2] - temp[0];
}

int Dfs(int u, int p) {
    int ret = inf;
    vector<int> closest;

    {
        closest = findClosest(in, (n + sz[u]) / 2);
        Fe (vsz : closest) {
            chmin(ret, findDiff(sz[u], vsz - sz[u], n - vsz));
        }
    }
    {
        closest = findClosest(out, (n - sz[u]) / 2);
        Fe (vsz : closest) {
            chmin(ret, findDiff(sz[u], vsz, n - sz[u] - vsz));
        }
    }

    in.insert(sz[u]);
    Fe (v : g[u]) {
        if (v != p) {
            chmin(ret, Dfs(v, u));
        }
    }
    in.erase(in.find(sz[u]));
    out.insert(sz[u]);

    return ret;
}

signed main() {
    cin >> n;
    For (i, 1, n - 1) {
        int u, v; cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    DfsSize(1, -1);

    cout << Dfs(1, -1) << '\n';
}

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