제출 #1319342

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1319342		Trisanu_Das	선물 (IOI25_souvenirs)	C++20	0 / 100	0 ms	400 KiB

souvenirs

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

pair<vector<int>, long long> transaction(long long M);

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

    long long knownTailSum = 0;

    // Recover prices from high indices downward
    for (int i = N - 1; i >= 1; --i) {
        long long M = P0 - 1 - knownTailSum;
        auto res = transaction(M);

        long long selectedSum = M - res.second;

        long long tailContribution = 0;
        bool found = false;

        for (int idx : res.first) {
            if (idx > i)
                tailContribution += P[idx];
            if (idx == i)
                found = true;
        }

        if (found) {
            P[i] = selectedSum - tailContribution;
        } else {
            // probe boundary
            long long M2 = M - 1;
            auto res2 = transaction(M2);
            long long sel2 = M2 - res2.second;

            long long tail2 = 0;
            bool found2 = false;
            for (int idx : res2.first) {
                if (idx > i) tail2 += P[idx];
                if (idx == i) found2 = true;
            }

            if (found2)
                P[i] = sel2 - tail2;
            else
                P[i] = (M2 - tailContribution) + 1;
        }

        knownTailSum += P[i];
    }

    // Purchase required souvenirs
    for (int t = 1; t < N; ++t) {
        for (int rep = 0; rep < t; ++rep) {
            long long M = P[t];

            for (int j = N - 1; j > t; --j)
                if (M + P[j] < P0)
                    M += P[j];

            transaction(M);
        }
    }
}

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