Submission #999542

#	Time	Username	Problem	Language	Result	Execution time	Memory
999542		mdn2002	Closing Time (IOI23_closing)	C++17	100 / 100	384 ms	80640 KiB

closing

/*
Mayoeba Yabureru
*/
#include<bits/stdc++.h>
using namespace std;

int max_score(int n, int x, int y, long long k, vector<int> U, vector<int> V, vector<int> W) {
    x ++, y ++;
    vector dis(n + 1, vector<long long>(2));
    vector<vector<pair<int, long long>>> gr(n + 1);

    for (int i = 0; i < n - 1; i ++) {
        int u = U[i] + 1, v = V[i] + 1, w = W[i];
        gr[u].push_back({v, w});
        gr[v].push_back({u, w});
    }

    function<void(int, int, int)> dfs = [&] (int v, int p, int wt) {
        for (auto [u, w] : gr[v]) {
            if (u == p) continue;
            dis[u][wt] = dis[v][wt] + w;
            dfs(u, v, wt);
        }
    };
    dfs(x, 0, 0), dfs(y, 0, 1);

    vector<int> vc, path, onpath(n + 1);
    function<void(int, int)> go = [&] (int v, int p) {
        vc.push_back(v);
        if (v == y) path = vc;
        for (auto [u, w] : gr[v]) {
            if (u == p) continue;
            go(u, v);
        }
        vc.pop_back();
    };
    go(x, 0);

    int ans = 0;
    function f = [&] {
        vector<int> did(n + 1);
        multiset<pair<long long, int>> s;
        for (int i = 1; i <= n; i ++) {
            s.insert({dis[i][0], i});
            s.insert({dis[i][1], i});
        }
        int cnt = 0;
        vector<int> v;

        while (s.size()) {
            auto [x, y] = *s.begin();
            s.erase(s.begin());
            if (did[y]) continue;
            if (x > k) break;
            k -= x;
            did[y] = 1;
            cnt ++;
        }
        if (k >= 0) return cnt;
        return -100000000;
    };

    long long kk = k;
    ans = f();
    k = kk;

    int cnt = 0;
    vector cost (n + 1, vector<long long> (2));
    for (int i = 1; i <= n; i ++) {
        cost[i][0] = min(dis[i][0], dis[i][1]);
        cost[i][1] = max(dis[i][0], dis[i][1]) - cost[i][0];
    }

    for (auto x : path) {
        k -= cost[x][0];
        cnt ++;
        onpath[x] = 1;
    }
    if (k < 0) return ans;

    set<pair<long long, int>> s, ss;
    for (int i = 1; i <= n; i ++) {
        if (onpath[i]) s.insert({cost[i][1], i});
        else {
            if (cost[i][0] > cost[i][1]) ss.insert({cost[i][0] + cost[i][1], i});
            else s.insert({cost[i][0], i});
        }
    }

    while (s.size()) {
        if (ss.size() == 0) {
            auto [a, x] = *s.begin();
            s.erase(s.begin());
            if (a > k) break;
            k -= a;
            cnt ++;
            onpath[x] ++;
            if (onpath[x] == 1) s.insert({cost[x][1], x});
        }
        else {
            long long mn = 1e17;
            auto [a, x] = *ss.begin();
            auto [b, y] = *s.begin();

            if (s.size() != 1) {
                auto [c, z] = * ++s.begin();
                mn = min(mn, b + c);
            }

            if (onpath[y] == 0) mn = min(mn, dis[y][0] + dis[y][1]);

            if (mn <= a || a > k) {
                s.erase(s.begin());
                if (b > k) break;
                k -= b;
                cnt ++;
                onpath[y] ++;
                if (onpath[y] == 1) s.insert({cost[y][1], y});
            }
            else {
                ss.erase(ss.begin());
                if (a > k) break;
                k -= a;
                cnt += 2;
            }
        }
    }

    multiset<pair<long long, int>> mss;
    while (ss.size()) {
        auto [a, x] = *ss.begin();
        ss.erase(ss.begin());
        mss.insert({cost[x][0], x});
    }

    while (mss.size()) {
        auto [a, x] = *mss.begin();
        mss.erase(mss.begin());
        if (a > k) break;
        k -= a;
        cnt ++;
    }
    return max(cnt, ans);
}
/*
1
7 0 2 10
0 1 2
0 3 3
1 2 4
2 4 2
2 5 5
5 6 3

*/

• 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