Submission #999544

#	Time	Username	Problem	Language	Result	Execution time	Memory
999544		Wael	Closing Time (IOI23_closing)	C++17	100 / 100	362 ms	80072 KiB

closing

#include "closing.h"
//#include "grader.cpp"
#include <bits/stdc++.h>
using namespace std;
using i64 = long long;

int max_score(int n, int x, int y, long long k, vector<int> U, vector<int> V, vector<int> W) {
    vector<vector<pair<int, int>>> adj(n);
    for (int i = 0; i < n - 1; ++i) {
        adj[U[i]].push_back({V[i], W[i]});
        adj[V[i]].push_back({U[i], W[i]});
    }

    vector<vector<i64>> dis(n, vector<i64>(2, 0));
    vector<vector<int>> next(n, vector<int>(2, -1));
    function<void(int, int, int)> dfs = [&](int u, int p, int t) {
        for (auto [v, w] : adj[u]) {
            if (v == p) continue;
            dis[v][t] = dis[u][t] + w;
            next[v][!t] = u;
            dfs(v, u, t);
        }
    };
    dfs(x, -1, 0);
    dfs(y, -1, 1);

    vector<int> path, onPath(n, 0);
    int z = x;
    while (true) {
        path.push_back(z);
        onPath[z] = 1;
        if (z == y) {
            break;
        }
        z = next[z][0];
    }
    
    vector<i64> one(n), two(n), upgCost(n);
    for (int u = 0; u < n; ++u) {
        one[u] = min(dis[u][0], dis[u][1]);
        two[u] = max(dis[u][0], dis[u][1]);
        upgCost[u] = two[u] - one[u];
    }

    vector<int> used(n, 0);
    auto work = [&](bool mark, i64 k) {
        int ret = 0;
        vector<bool> vis(n, 0);
        priority_queue<pair<i64, int>, vector<pair<i64, int>>, greater<pair<i64, int>>> pq;
        pq.push({0, x});
        pq.push({0, y});
        while (pq.size()) {
            auto [cost, u] = pq.top();
            pq.pop();
            if (cost > k) {
                break;
            }
            if (vis[u]) {
                continue;
            }

            vis[u] = 1;        
            k -= cost;
            ++ret;
            for (auto [v, w] : adj[u]) {
                pq.push({one[v], v});
            }
        }

        return ret;
    };
    int ans1 = work(0, k);

    int ans2 = 0;
    set<pair<i64, int>> upgrade;
    set<pair<i64, int>> take;
    set<pair<i64, int>> average;

    for (auto u : path) {
        k -= one[u];
        ++ans2;
        upgrade.insert({upgCost[u], u});
    }

    if (k < 0) {
        return ans1;
    }

    for (int u = 0; u < n; ++u) {
        if (onPath[u]) continue;
        take.insert({one[u], u});
        average.insert({two[u], u});
    }

    int last = -1;
    while (ans2 < 2 * n) {
        i64 mn = 1e18, type = 0;
        if (take.size()) {
            mn = take.begin() -> first;
            type = 1;
        }
        if (upgrade.size()) {
            if (upgrade.begin() -> first < mn) {
                type = 2;
            }
            mn = min(mn, upgrade.begin() -> first);
        }
        if (average.size()) {
            if ((average.begin() -> first + 1) / 2 <= mn && average.begin() -> first <= k) {
                type = 3;
            }
        }

        if (mn > k && type != 3) {
            break;
        }

        if (type == 1) {
            auto [cost, u] = *take.begin();
            k -= cost;
            average.erase({two[u], u});
            take.erase(take.begin());
            upgrade.insert({upgCost[u], u});
            ++ans2;
            last = cost;
        } else if (type == 2) {
            auto [cost, u] = *upgrade.begin();
            k -= cost;
            upgrade.erase(upgrade.begin());
            ++ans2;
            last = cost;
        } else if (type == 3) {
            auto [cost, u] = *average.begin();
            k -= cost;
            take.erase({one[u], u});
            average.erase(average.begin());
            ans2 += 2;
        }
    }
    if (average.size() && k + last >= average.begin() -> first) {
        ++ans2;
    }

    return max(ans1, ans2);
}

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