Submission #1250249

#	Time	Username	Problem	Language	Result	Execution time	Memory
1250249		gptopenai	Souvenirs (IOI25_souvenirs)	C++20	0 / 100	11 ms	400 KiB

souvenirs

#include "souvenirs.h"
#include <vector>
#include <algorithm>

// We know P[0] = P0.  We will fill in P[1..N-1] by binary search,
// then for each i = 1..N-1 we call transaction(P[i]) exactly i times
// to buy i souvenirs of type i.

void buy_souvenirs(int N, long long P0) {
    std::vector<long long> P(N);
    P[0] = P0;

    // 1) Learn P[1..N-1]:
    // For each i = 1..N-1, binary search P[i] in [1, P[i-1]-1].
    for (int i = 1; i < N; i++) {
        long long lo = 1, hi = P[i-1] - 1;
        while (lo < hi) {
            long long mid = (lo + hi) / 2;
            // mid < P[i-1] ≤ P0, so it's a valid M: 1 ≤ mid < P0
            auto res = transaction(mid);
            const auto &bought = res.first;
            // Did we buy type i?
            bool got_i = std::binary_search(bought.begin(), bought.end(), i);
            if (got_i) {
                // mid >= P[i], so P[i] ≤ mid
                hi = mid;
            } else {
                // mid < P[i]
                lo = mid + 1;
            }
        }
        P[i] = lo;
    }

    // 2) Now that we know all P[i], just buy exactly i of type i:
    //    calling transaction(P[i]) will buy exactly one of type i
    //    (and none cheaper, since after subtracting P[i] the remainder
    //     is zero), so repeat i times.
    for (int i = 1; i < N; i++) {
        for (int cnt = 0; cnt < i; cnt++) {
            transaction(P[i]);
        }
    }
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 4
• Subtask 2: 0 / 3
• Subtask 3: 0 / 14
• Subtask 4: 0 / 18
• Subtask 5: 0 / 28
• Subtask 6: 0 / 33