Submission #1316581

#TimeUsernameProblemLanguageResultExecution timeMemory
1316581lucas110550Festival (IOI25_festival)C++20
Compilation error
0 ms0 KiB
#include <bits/stdc++.h>
#include <boost/multiprecision/cpp_int.hpp>

using namespace std;
using boost::multiprecision::cpp_int;

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

    // coeff[t] = 12 * t / (t-1) for t=2..4
    const int coeff[5] = {0, 0, 24, 18, 16};

    // ---------- split coupons ----------
    vector<pair<long long,int>> cheap; // (price, idx) for T=1
    cheap.reserve(n);

    struct Booster {
        long long key; // p * coeff[t] (fits in int64 for p up to ~1e9)
        int p;
        int t;
        int idx;
    };
    vector<Booster> boosters;
    boosters.reserve(n);

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

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

    // cheap prefix sums in int64: with P up to 1e9 and N up to 2e5 => sum <= 2e14 fits
    vector<long long> cheap_psum(cheap.size() + 1, 0);
    vector<int> cheap_idx(cheap.size());
    for (size_t i = 0; i < cheap.size(); i++) {
        cheap_psum[i + 1] = cheap_psum[i] + cheap[i].first;
        cheap_idx[i] = cheap[i].second;
    }

    auto cheap_cnt_from_token = [&](const cpp_int& tok) -> int {
        // If tok is enormous, we can afford all cheap coupons.
        static const cpp_int LL_MAX = std::numeric_limits<long long>::max();
        if (tok >= LL_MAX) return (int)cheap.size();

        long long x = (long long)tok; // safe now
        auto it = upper_bound(cheap_psum.begin(), cheap_psum.end(), x);
        return int(it - cheap_psum.begin()) - 1; // k s.t. psum[k] <= x
    };

    // ---------- take all non-decreasing boosters ----------
    cpp_int token = A;
    vector<int> prefix_ids;
    prefix_ids.reserve(boosters.size());

    int i = 0, m = (int)boosters.size();
    while (i < m) {
        const auto &b = boosters[i];
        cpp_int p = b.p;
        cpp_int t = b.t;

        // token*(t-1) >= p*t  <=>  token >= p*t/(t-1)
        if (token * (t - 1) >= p * t) {
            prefix_ids.push_back(b.idx);
            token = (token - p) * t;
            i++;
        } else break;
    }

    // ---------- hard suffix DP ----------
    const int K = 61;
    int h_len = m - i;

    vector<cpp_int> dp(K + 1, cpp_int(-1));
    dp[0] = token;

    // parent[j][c] = 1 if using hard[j] sets dp[c] at iteration j
    vector<vector<uint8_t>> parent(h_len, vector<uint8_t>(K + 1, 0));

    for (int j = 0; j < h_len; j++) {
        const auto &b = boosters[i + j];
        cpp_int p = b.p;
        cpp_int t = b.t;

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

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

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

    // ---------- reconstruct chosen hard subset ----------
    vector<int> chosen_hard_pos;
    chosen_hard_pos.reserve(best_c);

    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 final answer ----------
    vector<int> answer;
    answer.reserve(prefix_ids.size() + chosen_hard_pos.size() + cheap.size());

    for (int id : prefix_ids) answer.push_back(id);
    for (int pos : chosen_hard_pos) answer.push_back(boosters[i + pos].idx);

    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;
}

Compilation message (stderr)

festival.cpp:2:10: fatal error: boost/multiprecision/cpp_int.hpp: No such file or directory
    2 | #include <boost/multiprecision/cpp_int.hpp>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.