Submission #401216

#	Time	Username	Problem	Language	Result	Execution time	Memory
401216		galca	A Difficult(y) Choice (BOI21_books)	C++14	25 / 100	2 ms	1152 KiB

books

#include <iostream>
#include <vector>
using namespace std;

#include "books.h"

int findA(vector<long long>& books, long long A, int lower, int upper) {
	if (books[lower] == -1) {
		books[lower] = skim(lower + 1);
	}
	if (books[upper] == -1) {
		books[upper] = skim(upper + 1);
	}
	if (books[lower] > A) {
		return lower;
	}
	if (books[upper] < A) {
		return -1;
	}

	if (upper - lower < 2) {
		return upper;
	}

	int half = (upper - lower + 1) / 2;
	books[lower + half] = skim(lower + half + 1);

	if (books[lower + half] < A) return findA(books, A, lower + half, upper);
	else return findA(books, A, lower, lower + half);
}

void solve(int N, int K, long long A, int S) {
	if (K > N) {
		impossible();
		return;
	}
	vector<long long> books(N);

	for (int i = 0; i < N; i++) {
		books[i] = -1;
	}

	long long sumFirstK = 0;
	for (int i = 0; i < K; i++) {
		if (books[i] == -1) {
			books[i] = skim(i + 1);
		}
		sumFirstK += books[i];
	}

	if (sumFirstK > A * 2) {
		impossible();
	}
	else {
		vector<int> res;
		for (int i = 0; i < K; i++) {
			res.push_back(i + 1);
		}
		if (sumFirstK >= A) {
			answer(res);
		}
		else {
			// sumFirstK < A
			long long posA = findA(books, A, 0, N - 1);
			if (posA != -1) {
				res[K-1] = posA + 1;
				answer(res);
			}
			else {
				// all elements < A and the sum of first k is < A
				// sample last k
				for (int i = 0; i < K; i++) {
					if (books[N - 1 - i] == -1) {
						books[N - 1 - i] = skim(N - i);
					}
					sumFirstK -= books[i];
					res[i] = N - i;
					sumFirstK += books[N - 1 - i];
					if (sumFirstK >= A) {
						answer(res);
						break;
					}
				}
				impossible();
			}
		}
	}
	return;
}

• 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