제출 #1316575

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1316575		lucas110550	축제 (IOI25_festival)	C++20	48 / 100	74 ms	33056 KiB

festival

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

std::vector<int> max_coupons(int A, std::vector<int> P, std::vector<int> T) {
    int n = (int)P.size();

    // ---------- split coupons ----------
    vector<pair<long long,int>> cheap; // (price, original_index) for T=1
    struct Booster {
        long long key; // pi * coeff[ti]
        int p;
        int t;
        int idx;
    };
    vector<Booster> boosters; // for T>1

    // coeff = 12*T/(T-1) for T in {2,3,4}
    unordered_map<int,int> coeff{{2,24},{3,18},{4,16}};

    int max_price = 0;
    for (int i = 0; i < n; i++) {
        int ti = T[i];
        int pi = P[i];
        if (ti == 1) {
            cheap.push_back({pi, i});
        } else {
            long long key = 1LL * pi * coeff[ti];
            boosters.push_back({key, pi, ti, i});
            max_price = max(max_price, pi);
        }
    }

    // ---------- sort ----------
    sort(cheap.begin(), cheap.end(),
         [](const auto& a, const auto& b){ return a.first < b.first; }); // cheapest first

    sort(boosters.begin(), boosters.end(),
         [](const Booster& a, const Booster& b){
            if (a.key != b.key) return a.key < b.key;
            return a.p < b.p;
         });

    vector<long long> cheap_prices;
    vector<int> cheap_idx;
    cheap_prices.reserve(cheap.size());
    cheap_idx.reserve(cheap.size());
    for (auto &pr : cheap) {
        cheap_prices.push_back(pr.first);
        cheap_idx.push_back(pr.second);
    }

    // prefix sums of cheap prices
    vector<long long> cheap_psum(cheap_prices.size() + 1, 0);
    for (size_t i = 0; i < cheap_prices.size(); i++) {
        cheap_psum[i + 1] = cheap_psum[i] + cheap_prices[i];
    }

    // ---------- take all non-decreasing boosters ----------
    long long token = A;
    vector<int> prefix_ids; // original indices of taken prefix boosters
    int i = 0;
    int m = (int)boosters.size();

    while (i < m) {
        const auto &b = boosters[i];
        long long p = b.p;
        long long t = b.t;
        // token * (t-1) >= p * t
        if (token * (t - 1) >= p * t) {
            prefix_ids.push_back(b.idx);
            token = (token - p) * t;
            i++;
        } else {
            break;
        }
    }

    // ---------- hard suffix ----------
    vector<Booster> hard;
    hard.reserve(m - i);
    for (int j = i; j < m; j++) hard.push_back(boosters[j]);
    int h_len = (int)hard.size();

    const int K = 61; // safe upper bound
    vector<long long> dp(K + 1, -1);
    dp[0] = token;

    // parent[j][c] = 1 iff hard[j] is used to achieve dp[c] at step j
    vector<vector<uint8_t>> parent(h_len, vector<uint8_t>(K + 1, 0));

    for (int j = 0; j < h_len; j++) {
        long long p = hard[j].p;
        long long t = hard[j].t;
        int max_c = min(j + 1, K);
        for (int c = max_c; c >= 1; c--) {
            long long prev = dp[c - 1];
            if (prev >= p) {
                long long cand = (prev - p) * t;
                if (cand > dp[c]) {
                    dp[c] = cand;
                    parent[j][c] = 1;
                }
            }
        }
    }

    // ---------- evaluate all possibilities ----------
    int best_total = -1;
    int best_c = 0;
    long long best_token = dp[0];

    auto cheap_cnt_from_token = [&](long long tok) -> int {
        // number of cheap items affordable = max k s.t. cheap_psum[k] <= tok
        auto it = upper_bound(cheap_psum.begin(), cheap_psum.end(), tok);
        return int(it - cheap_psum.begin()) - 1;
    };

    for (int c = 0; c <= min(K, h_len); c++) {
        long long cur = dp[c];
        if (cur < 0) continue;
        int cheap_cnt = cheap_cnt_from_token(cur);
        int total = i + c + cheap_cnt; // i boosters from prefix + c from hard + cheap_cnt
        if (total > best_total) {
            best_total = total;
            best_c = c;
            best_token = cur;
        }
    }

    // ---------- reconstruct the chosen hard subset ----------
    vector<int> chosen_hard_pos;
    int need = best_c;
    for (int j = h_len - 1; j >= 0 && need > 0; j--) {
        if (parent[j][need]) {
            chosen_hard_pos.push_back(j);
            need--;
        }
    }
    reverse(chosen_hard_pos.begin(), chosen_hard_pos.end());

    // ---------- build the final answer ----------
    vector<int> answer;
    answer.reserve(prefix_ids.size() + chosen_hard_pos.size() + cheap_idx.size());

    // prefix boosters
    for (int id : prefix_ids) answer.push_back(id);

    // selected hard boosters (append original indices)
    for (int pos : chosen_hard_pos) {
        answer.push_back(hard[pos].idx);
    }

    // cheap coupons (as many as affordable with best_token)
    int cheap_cnt_final = cheap_cnt_from_token(best_token);
    for (int k = 0; k < cheap_cnt_final; k++) {
        answer.push_back(cheap_idx[k]);
    }

    return answer;
}

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• Subtask 1: 5 / 5
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• Subtask 6: 16 / 16
• Subtask 7: 0 / 18