Submission #1206194

#	Time	Username	Problem	Language	Result	Execution time	Memory
1206194		Triseedot	Cat Exercise (JOI23_ho_t4)	C++20	100 / 100	248 ms	67768 KiB

Main

// Made by ordinary newbie

#pragma region setup
#include <bits/stdc++.h>
#include <random>
#include <chrono>
using namespace std;

// variables
#define int long long
using ld = long double;
using ll = long long;
using ull = unsigned long long;
template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
// bitwise operations
#define cnt_bit(n) __builtin_popcountll(n)
#define low_bit(n) ((n) & (-(n)))
#define bit(n, i) (((n) >> (i)) & 1)
#define set_bit(n, i) ((n) | (1ll << (i)))
#define reset_bit(n, i) ((n) & ~(1ll << (i)))
#define flip_bit(n, i) ((n) ^ (1ll << (i)))
// math
#define sqr(n) ((n) * (n))
int log2_floor(ull n) {
    return n ? __builtin_clzll(1) - __builtin_clzll(n) : -1;
}
const ll INF = 1e18;
// utils
#define len(x) (int) x.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
    for(auto& el : v) {
        is >> el;
    }
    return is;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    for (int i = 0; i < len(v); i++) {
        if (i) os << ' ';
        os << v[i];
    }
    return os;
}
template<class... Args>
auto create(size_t n, Args&&... args) {
    if constexpr(sizeof...(args) == 1) {
        return vector(n, args...);
    }
    else {
        return vector(n, create(args...));
    }
}
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
    size_t operator()(pair<int, int> x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x.first + FIXED_RANDOM) ^ splitmix64(x.second + FIXED_RANDOM);
    }
};
template<typename T, typename U>
bool chmin(T& a, const U b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U>
bool chmax(T& a, const U b) {
    if (b > a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T>
void compress(vector<T>& v) {
    int n = len(v);
    vector<pair<T, int>> u(n);
    for (int i = 0; i < n; i++) {
        u[i] = {v[i], i};
    }
    sort(all(u));
    int curr = 0;
    for (int i = 0; i < n; i++) {
        if (i != 0 && u[i].first != u[i - 1].first) curr++;
        v[u[i].second] = curr;
    }
}
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
#pragma endregion

struct DSU {
    int n;
    vector<int> p;

    DSU(int N) {
        n = N;
        p.resize(n);
        iota(all(p), 0);
    }

    int get(int v) {
        if (p[v] == v) return v;
        return p[v] = get(p[v]);
    }

    bool unite(int v, int u) {
        v = get(v), u = get(u);
        if (v == u) return false;
        p[v] = u;
        return true;
    }
};

const int L = 20;
void solve() {
    int n;
    cin >> n;
    vector<int> p(n);
    cin >> p;
    vector<int> pi(n);
    for (int i = 0; i < n; i++) {
        pi[p[i] - 1] = i;
    }

    vector<vector<int>> g(n);
    for (int i = 0; i < n - 1; i++) {
        int v, u;
        cin >> v >> u;
        v--, u--;
        g[v].push_back(u);
        g[u].push_back(v);
    }

    vector<int> tin(n), tout(n), depth(n, 0);
    vector binup = create(n, L, 0);
    int timer = 0;
    function<void(int, int)> dfs = [&] (int v, int pr) {
        binup[v][0] = pr;
        for (int i = 1; i < L; i++) {
            binup[v][i] = binup[binup[v][i - 1]][i - 1];
        }
        tin[v] = timer++;
        for (int u : g[v]) {
            if (u == pr) continue;
            depth[u] = depth[v] + 1;
            dfs(u, v);
        }
        tout[v] = timer;
    };
    dfs(0, 0);

    auto is_pr = [&] (int pr, int v) {
        return tin[pr] <= tin[v] && tout[v] <= tout[pr];
    };
    auto dist = [&] (int v, int u) {
        int w = v;
        for (int i = L - 1; i >= 0; i--) {
            if (!is_pr(binup[w][i], u)) {
                w = binup[w][i];
            }
        }
        if (!is_pr(w, u)) {
            w = binup[w][0];
        }
        return depth[v] + depth[u] - 2 * depth[w];
    };

    vector<int> dp(n, -1);
    DSU dsu(n);
    for (int v : pi) {
        dp[v] = 0;
        for (int u : g[v]) {
            if (dp[u] == -1) continue;
            u = dsu.get(u);
            chmax(dp[v], dp[u] + dist(v, u));
            dsu.unite(u, v);
        }
    }

    cout << dp[pi.back()] << '\n';
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int tt = 1;
    //cin >> tt;
    for (int i = 1; i <= tt; i++) {
        solve();
    }
}

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 23 / 23
• Subtask 7: 26 / 26