Submission #889637

#	Time	Username	Problem	Language	Result	Execution time	Memory
889637		shiomusubi496	A Difficult(y) Choice (BOI21_books)	C++17	100 / 100	1 ms	1620 KiB

books

#include <bits/stdc++.h>

#include "books.h"

using namespace std;

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rrep(i, n) for (int i = (int)(n) - 1; i >= 0; --i)

using ll = long long;

void solve(int N, int K, long long A, int S) {
    auto my_skim = [&](int pos) {
        static vector<ll> memo(N, -1);
        if (memo[pos] != -1) return memo[pos];
        return memo[pos] = skim(pos + 1);
    };
    ll sm = 0;
    rep (i, K - 1) sm += my_skim(i);
    int ok = K - 2, ng = N;
    while (ng - ok > 1) {
        int mid = (ok + ng) / 2;
        if (sm + my_skim(mid) < A) ok = mid;
        else ng = mid;
    }
    if (ok != N - 1 && sm + my_skim(ok + 1) <= 2 * A) {
        vector<int> ans;
        rep (i, K - 1) ans.push_back(i + 1);
        ans.push_back(ok + 2);
        answer(ans);
        return;
    }
    if (ok == K - 2) {
        impossible();
        return;
    }
    sm += my_skim(ok);
    rep (i, K - 1) {
        sm -= my_skim(K - 2 - i);
        sm += my_skim(ok - i - 1);
        if (sm >= A) {
            vector<int> ans;
            rep (j, K - 2 - i) ans.push_back(j + 1);
            rrep (j, i + 2) ans.push_back(ok - j + 1);
            answer(ans);
            return;
        }
    }
    impossible();
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 10 / 10
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 20 / 20
• Subtask 7: 20 / 20