Submission #409228

#	Time	Username	Problem	Language	Result	Execution time	Memory
409228		jamielim	A Difficult(y) Choice (BOI21_books)	C++14	100 / 100	2 ms	1072 KiB

books

#include <bits/stdc++.h>

#include "books.h"

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

#define fi first
#define se second
#define mp make_pair
#define pb emplace_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
typedef long long ll;
typedef pair<int,int> ii;
typedef pair<ii,ii> i4;
const int MOD=1000000007;
const int INF=1012345678;
const ll LLINF=1012345678012345678LL;
const double PI=3.1415926536;
const double EPS=1e-14;

ll arr[100005];

ll get(int x){
	if(arr[x]==-1)arr[x]=skim(x);
	return arr[x];
}

void solve(int N, int K, long long A, int S) {
    memset(arr,-1,sizeof(arr));
    int l=1,r=N;
    while(l<r){
		int m=(l+r+1)/2;
		if(get(m)<A){
			l=m;
		}else{
			r=m-1;
		}
	}
	if(l<=K-2){
		impossible();
		return;
	}
	if(l==K-1){
		ll sum=0;
		vector<int> v;
		for(int i=1;i<=K;i++){
			sum+=get(i);
			v.pb(i);
		}
		if(sum<A||sum>2*A)impossible(); // sum<A should not happen since get(K)>=A
		else answer(v);
		return;
	}
	ll small=0,large=0;
	for(int i=1;i<=K;i++)small+=get(i);
	for(int i=l;i>l-K;i--)large+=get(i);
	if(small>2*A){impossible();return;}
	if(large<A){
		vector<int> v;for(int i=1;i<K;i++)v.pb(i);v.pb(l+1);
		if(l+1<=N&&small-get(K)+get(l+1)<=2*A)answer(v);
		else impossible();
		return;
	}
	// small<=2A, large>=A
	ll sum=small;
	for(int i=K;i>=1;i--){
		if(sum>=A){
			vector<int> v;
			for(int j=1;j<=i;j++){
				v.pb(j);
			}
			for(int j=l-K+i+1;j<=l;j++){
				v.pb(j);
			}
			answer(v);
			return;
		}
		sum-=get(i);
		sum+=get(l-K+i);
	}
	if(sum>=A){
		vector<int> v;
		for(int j=l-K+1;j<=l;j++)v.pb(j);
		answer(v);
		return;
	}
	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