Submission #981606

#	Time	Username	Problem	Language	Result	Execution time	Memory
981606		OAleksa	A Difficult(y) Choice (BOI21_books)	C++14	45 / 100	1 ms	856 KiB

books

#include <bits/stdc++.h>

#include "books.h"

using namespace std;
const int N = 1e5 + 69;
long long was[N], sum = 0;
//
// --- 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) {
	int l = 1, r = n, lst = -1;
	vector<int> ans;
	while (l <= r) {
		int mid = (l + r) / 2;
		long long b = 0;
		if (was[mid] > 0)
			b = was[mid];
		else
			b = skim(mid);
		was[mid] = b;
		if (b >= a) {
			lst = mid;
			r = mid - 1;
		}
		else
			l = mid + 1;
	}
	if (lst == -1) {
		for (int i = n, j = 0;i >= 1, j < k;j++, i--) {
			if (!was[i])
				was[i] = skim(i);
			sum += was[i];
		}
		if (sum < a)
			impossible();
		else if (sum >= a && sum <= 2 * a) {
			for (int i = n,j = 0;i >= 1,j < k;i--,j++)
				ans.push_back(i);
			answer(ans);
		}
		long long ss = 0;
		for (int i = 1;i <= k;i++) {
			if (!was[i])
				was[i] = skim(i);
			ss += was[i];
		}
		if (ss > 2 * a)
			impossible();
		else if (ss >= a && ss <= 2 * a) {
			for (int i = 1;i <= k;i++)
				ans.push_back(i);
			answer(ans);
		}
		int ptr = n, d = 0;
		while (d < k) {
			sum -= was[ptr];
			sum += was[n - ptr + 1];
			ptr--;
			d++;
			if (sum >= a && sum <= 2 * a)
				break;
		}
		for (int i = 1;i <= d;i++)
			ans.push_back(i);
		for (int i = n - k + 1;i <= ptr;i++)
			ans.push_back(i);
		assert(sum >= a && sum <= 2 * a);
		answer(ans);
	}
	else if (lst < k)
		impossible();
	for (int i = 1;i <= k - 1;i++) {
		was[i] = skim(i);
		sum += was[i];
	}
	sum += was[lst];
	if (sum >= a && sum <= 2 * a) {
		for (int i = 1;i <= k - 1;i++)
			ans.push_back(i);
		ans.push_back(lst);
		answer(ans);
	}
	sum -= was[lst];
	long long t = a - sum;
	if (sum >= a) {
		sum = 0;
		for (int i = 1;i <= k;i++) {
			ans.push_back(i);
			if (!was[i])
				was[i] = skim(i);
			sum += was[i];
		}
		if (sum >= a && sum <= 2 * a)
			answer(ans);
		assert(sum >= a);
		impossible();
	}
	int ll = k - 1;
	l = k, r = lst - 1;
	int id = -1;
	for (int i = k;i < lst;i++) {
		if (was[i]) {
			if (t >= was[ll] && t <= was[i])
				l = ll, r = i;
			ll = i;
		}
	}
	while (l <= r) {
		int mid = (l + r) / 2;
		long long b = 0;
		if (was[mid])
			b = was[mid];
		else
			b = skim(mid);
		was[mid] = b;
		if (b < t) {
			id = mid;
			l = mid + 1;
		}
		else 
			r = mid - 1;
	}
	if (id == -1 || id + 1 == lst)
		impossible();
	for (int i = 1;i <= k - 1;i++)
		ans.push_back(i);
	ans.push_back(id + 1);
	long long ss = sum + skim(id + 1);
	assert(ss >= a && ss <= 2 * a);
	answer(ans);
}

Compilation message (stderr)

books.cpp: In function 'void solve(int, int, long long int, int)':
books.cpp:37:27: warning: left operand of comma operator has no effect [-Wunused-value]
   37 |   for (int i = n, j = 0;i >= 1, j < k;j++, i--) {
      |                         ~~^~~~
books.cpp:45:27: warning: left operand of comma operator has no effect [-Wunused-value]
   45 |    for (int i = n,j = 0;i >= 1,j < k;i--,j++)
      |                         ~~^~~~

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