Submission #943283

#	Time	Username	Problem	Language	Result	Execution time	Memory
943283		teacup	A Difficult(y) Choice (BOI21_books)	C++14	100 / 100	1 ms	1368 KiB

books

#include <bits/stdc++.h>

#include "books.h"

using namespace std;
#define ll long long
#define ii pair<int,int>
#define vi vector<int>
typedef vector<ii> vii;
//
// --- 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) {
    // TODO implement this function
    vector<long long> V(N+5);
    vector<int> ans;
    for (int i=0; i<N+5; i++) V[i]=-1;
    long long sum=0;
    for (int i=1; i<=K; i++){
		V[i]=skim(i);
		sum+=V[i];
	}
	if (sum>2*A){
		impossible();
	}else if (sum>=A){
		//answer!!
		ans.clear();
		for (int i=1; i<=K; i++){
			ans.push_back(i);
		}
		answer(ans);
	}else{
		//sum<A
		ans.clear();
		//binary search from K+1 to N
		ll L=1, R=N+1, M;
		while (L<R) {
			M = (L+R)/2;
			ll temp;
			
			if(V[M] != -1) temp = V[M];
            else temp = skim(M);
            V[M] = temp;
            
			if (temp < A) L = M+1;
			else R = M;
		}
		
		if (L < K) impossible();
		if (L <= N){
            ll temp;
			
			if(V[L] != -1) temp = V[L];
            else temp = skim(L);
            V[L] = temp;
 
            if(sum - V[K] + temp <= 2*A){
				ans.clear();
                for(int i=1; i<K; i++){
                    ans.push_back(i);
                }
                ans.push_back(L);
                answer(ans);
            }
            N = L - 1;
        }
 
        set<int> S_;
 
        for(int i=1; i<=K; i++){
            S_.insert(i);
        }
 
        for(int i=0; i<K; i++){
            S_.erase(K - i);
            S_.insert(N - i);
 
            ll temp;
 
            if(V[N - i] != -1) temp = V[N - i];
            else temp = skim(N - i);
            V[N - i] = temp;
 
            sum -= V[K - i];
            sum += temp;
 
            if(A <= sum && sum <= 2*A){
				ans.clear();
                for(int i : S_){
                    ans.push_back(i);
                }
                answer(ans);
            }
        }
        impossible();
	}
}

• 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