Submission #406664

#	Time	Username	Problem	Language	Result	Execution time	Memory
406664		jamezzz	A Difficult(y) Choice (BOI21_books)	C++14	100 / 100	4 ms	328 KiB

books

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

#include "books.h"

typedef long long ll;
//less_equal for identical elements
//
// --- 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.
//

int n;
long long a[100005];
bool use[100005];

ll arr(int i){
	if(a[i]!=0)return a[i];
	else return a[i]=skim(i);
}

void done(){
	vector<int> ans;
	for(int i=1;i<=n;++i){
		if(use[i])ans.push_back(i);
	}
	answer(ans);
}

void solve(int N, int K, long long A, int S) {
	n=N;
	ll sm=0;
	for(int i=1;i<=K;++i){
		sm+=arr(i);
		use[i]=true;
	}
	if(A<=sm&&sm<=2*A)done();
	else if(sm>2*A)impossible();
	int lo=1,hi=N,mid,res=0;
	while(lo<=hi){
		mid=(lo+hi)/2;
		if(arr(mid)<=A){
			res=mid;
			lo=mid+1;
		}
		else hi=mid-1;
	}
	if(res<=K)impossible();
	for(int i=K;i>=1;--i){
		if(sm-arr(i)+arr(res-(K-i))<=2*A){
			sm=sm-arr(i)+arr(res-(K-i));
			use[i]=false;
			use[res-(K-i)]=true;
		}
	}
	if(A<=sm)done();
	else if(res==N)impossible();
	sm=0;
	memset(use,false,sizeof use);
	for(int i=1;i<=K-1;++i){
		sm+=arr(i);
		use[i]=true;
	}
	use[res+1]=true;
	sm+=arr(res+1);
	for(int i=K-1;i>=1;--i){
		if(sm-arr(i)+arr(res-(K-1-i))<=2*A){
			sm=sm-arr(i)+arr(res-(K-1-i));
			use[i]=false;
			use[res-(K-1-i)]=true;
		}
	}
	if(sm<A||sm>2*A)impossible();
	else done();
}

• 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