Submission #950659

#	Time	Username	Problem	Language	Result	Execution time	Memory
950659		Pring	A Difficult(y) Choice (BOI21_books)	C++17	100 / 100	1 ms	600 KiB

books

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

#define fs first
#define sc second
#define mp make_pair
#define FOR(i, j, k) for (int i = j, Z = k; i < Z; i++)
typedef pair<int, int> pii;
using ll = long long;

namespace {
    const int MXN = 10;
    int n, k, s;
    ll a;
    int b;
    vector<int> v;
    ll l[MXN], r[MXN];

    int BSH(int l, int r, ll b) {
        while (l + 1 < r) {
            int mid = (l + r) >> 1;
            (skim(mid) >= b ? r : l) = mid;
        }
        return r;
    }

    void SOLVE() {
        b = BSH(0, n + 1, a);
        // if (b < k) {
        //     impossible();
        //     return;
        // }
        FOR(i, 0, k) l[i] = skim(i + 1);
        {
            ll acc = 0;
            FOR(i, 0, k) acc += l[i];
            if (acc > 2 * a) {
                impossible();
                return;
            }
            if (acc >= a) {
                FOR(i, 1, k + 1) v.push_back(i);
                answer(v);
                return;
            }
        }
        if (b != n + 1) {
            ll c = skim(b);
            ll acc = 0;
            FOR(i, 0, k - 1) acc += l[i];
            acc += c;
            if (acc <= 2 * a) {
                FOR(i, 1, k) v.push_back(i);
                v.push_back(b);
                answer(v);
                return;
            }
        }
        if (b == k) {
            impossible();
            return;
        }
        FOR(i, 0, k) r[i] = skim(b - k + i);
        // ll acc = 0;
        // FOR(i, 0, k) acc += r[i];
        // if (acc < a) {
        //     impossible();
        //     return;
        // }
        // if (acc <= 2 * a) {
        //     FOR(i, 0, k) v.push_back(b - k + i);
        //     answer(v);
        //     return;
        // }
        FOR(i, 0, k + 1) {
            // acc -= r[i];
            // acc += l[i];
            // if (acc <= 2 * a) {
            //     FOR(j, 0, i + 1) v.push_back(j);
            //     FOR(j, i + 1, k) v.push_back(b - k + j);
            //     answer(v);
            //     return;
            // }
            ll acc = 0;
            FOR(j, 0, i) acc += l[j];
            FOR(j, i, k) acc += r[j];
            if (a <= acc && acc <= 2 * a) {
                FOR(j, 0, i) v.push_back(j + 1);
                FOR(j, i, k) v.push_back(b - k + j);
                answer(v);
                return;
            }
        }
        impossible();
    }
}

void solve(int n, int k, ll a, int s) {
    ::n = n;
    ::k = k;
    ::a = a;
    ::s = s;
    SOLVE();
}

• 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