Submission #843402

#	Time	Username	Problem	Language	Result	Execution time	Memory
843402		I_love_Hoang_Yen	Closing Time (IOI23_closing)	C++17	8 / 100	218 ms	46716 KiB

closing

#include "closing.h"
#include <bits/stdc++.h>
using namespace std;
 
using ll = long long;
using Graph = vector<vector<pair<int,ll>>>;
 
void dfs(int u, int fu, const Graph& g, vector<ll>& dists) {
    for (auto [v, w] : g[u]) {
        if (v == fu) continue;
        assert(dists[v] < 0);
 
        dists[v] = dists[u] + w;
        dfs(v, u, g, dists);
    }
}
 
vector<ll> get_dists(int u, const Graph& g) {
    int n = g.size();
    vector<ll> dists(n, -1);
    dists[u] = 0;
 
    dfs(u, -1, g, dists);
    return dists;
}
 
int no_common(ll k, const vector<ll>& dx, const vector<ll>& dy) {
    vector<ll> all;
    for (auto d : dx) all.push_back(d);
    for (auto d : dy) all.push_back(d);
    sort(all.begin(), all.end());
    int cnt = 0;
    for (auto d : all) {
        if (d <= k) {
            k -= d;
            ++cnt;
        } else break;
    }
    return cnt;
}
 
// linear graph
struct Event {
    ll cost;
    int i;
    int typ;  // 1 = SINGLE, 2 = PAIR
};
bool operator < (const Event& a, const Event& b) {
    return a.cost * (3 - a.typ) < b.cost * (3 - b.typ);
}
 
int sub4(int n, ll k, int x, int y,
        const vector<ll>& dx, const vector<ll>& dy) { // x < y
    int res = no_common(k, dx, dy);
 
    // 0 .. [xl .. x .. xr]
    //               [yl .. y .. yr] .. n-1
    // Now we only consider the case where [xl, xr] and [yl, yr] overlap
    // They must overlap at least one point between [x, y]
 
    int cur = 0;
    set<Event> events;
    for (int i = 0; i < n; ++i) {
        auto a = min(dx[i], dy[i]);
        auto b = max(dx[i], dy[i]);

        if (x <= i && i <= y) {
            k -= a;
            ++cur;
            events.insert(Event{b - a, i, 2});
        } else {
            events.insert(Event{a, i, 1});
        }
    }
 
    if (k >= 0) {
        while (!events.empty()) {
            Event event = *events.begin();
            events.erase(events.begin());

            if (event.cost > k) break;
            k -= event.cost;
            if (event.typ == 1) {
                auto a = min(dx[event.i], dy[event.i]);
                auto b = max(dx[event.i], dy[event.i]);
                events.insert(Event{b - a, event.i, 2});
            }
        }
        res = max(res, cur);
    }
    return res;
}
 
int max_score(int n, int X, int Y, long long K,
              vector<int> U, vector<int> V, vector<int> W) {
    Graph g(n);
    assert(int(U.size()) == n-1);
    assert(int(V.size()) == n-1);
    assert(int(W.size()) == n-1);
    for (int i = 0; i < n - 1; i++) {
        int u = U[i];
        int v = V[i];
        int w = W[i];
        g[u].emplace_back(v, w);
        g[v].emplace_back(u, w);
    }
    if (X > Y) swap(X, Y);
 
    auto distsX = get_dists(X, g);
    auto distsY = get_dists(Y, g);
    
    return sub4(n, K, X, Y, distsX, distsY);
}

• Subtask 0: 0 / 0
• Subtask 1: 8 / 8
• Subtask 2: 0 / 9
• Subtask 3: 0 / 12
• Subtask 4: 0 / 14
• Subtask 5: 0 / 9
• Subtask 6: 0 / 11
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 17