Submission #1017602

#	Time	Username	Problem	Language	Result	Execution time	Memory
1017602		toast12	A Difficult(y) Choice (BOI21_books)	C++14	25 / 100	1 ms	596 KiB

books

#include "books.h"
#include <vector>
#include <iostream>
using namespace std;

using ll = long long;
//
// --- Sample implementation for the task books ---
//
// To compile this program with the sample grader, place:
//     books.h books_sample.cpp sample_grader.cpp
// in a single folder and run:
//     g++ books_sample.cpp sample_grader.cpp
// in this folder.
//

void solve(int N, int K, long long A, int S) {
    vector<int> a(K+1);
    vector<ll> books(K+1);
    ll sum = 0;
    for (int i = 1; i <= K; i++) {
        a[i] = i;
        books[i] = skim(i);
        sum += books[i];
    }
    if (sum > 2*A) {
        impossible();
        return;
    }
    if (sum >= A && sum <= 2*A) {
        vector<int> ans;
        for (int i = 1; i <= K; i++)
            ans.push_back(a[i]);
        answer(ans);
        return;
    }
    int lo = 1, hi = N;
    // find the first book larger than A
    while (lo < hi) {
        int mid = (lo+hi)/2;
        ll x = skim(mid);
        if (mid > A)
            hi = mid;
        else
            lo = mid+1;
    }
    int idx = hi;
    for (int i = K; i >= 1; i--) {
        // move the ith book to the end
        sum -= books[i];
        ll x = skim(idx);
        if (sum+x >= A && sum+x <= 2*A) {
            a[i] = idx;
            break;
        }
        else if (sum+x < A) {
            sum += x;
            books[i] = x;
            a[i] = idx;
            idx--;
        }
        else {
            int l = a[i]+1, r = idx-1;
            a[i] = -1;
            while (l < r) {
                int mid = (l+r)/2;
                ll d = skim(mid);
                if (sum+d >= A && sum+d <= 2*A) {
                    a[i] = mid;
                    break;
                }
                if (sum+d < A) {
                    l = mid+1;
                }
                else {
                    r = mid;
                }
            }
            if (a[i] == -1)
                impossible();
            break;
        }
    }
    vector<int> ans;
    for (int i = 1; i <= K; i++) {
        ans.push_back(a[i]);
    }
    answer(ans);
}

Compilation message (stderr)

books.cpp: In function 'void solve(int, int, long long int, int)':
books.cpp:41:12: warning: unused variable 'x' [-Wunused-variable]
   41 |         ll x = skim(mid);
      |            ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 15
• Subtask 3: 10 / 10
• Subtask 4: 15 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 20
• Subtask 7: 0 / 20