Submission #530629

#	Time	Username	Problem	Language	Result	Execution time	Memory
530629		huangqr	A Difficult(y) Choice (BOI21_books)	C++14	100 / 100	2 ms	296 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_sample.cpp sample_grader.cpp
// in a single folder and run:
//     g++ books_sample.cpp sample_grader.cpp
// in this folder.
//#include<bits/stdc++.h>
using namespace std;
typedef long long ll;


void solve(int N, int K, long long A, int S) {
    // TODO implement this function
    map<ll,ll>a;
	vector<int>ret;
	ll cur=0;
    for(int i=1;i<=K;i++)a[i]=skim(i),cur+=a[i];
	if(cur >= A && cur <= 2*A){
		for(int i=1;i<=K;i++)ret.push_back(i);
		answer(ret);
	}
	ll bound = N+1;
	a[N+1]=3e18; //inf
	for(int i=K;i>=1;i--){
		cur -= a[i];
		
		ll upper_add_limit = 2*A-cur;
		auto it = a.begin();
		while(it->second <= upper_add_limit)it++;
		bound = min(bound,it->first); //Bound is now the index of the first exceeding known point
		
		/*cout<<"i: "<<i<<" upper_add_limit:"<<upper_add_limit<<"\n";
		cout<<"i: "<<i<<" a:";
		for(auto x:a)cout<<x.first<<"->"<<x.second<<" ";
		cout<<"\n";
		cout<<"i: "<<i<<" bound:"<<bound<<"\n";*/
		
		
		if(bound <= i+1)impossible();
		it--;
		ll search_left = min(bound-1,it->first);
		ll search_right = bound-1; //[search_left, search_right] is the region where the last good point may be
		ll best = search_left;
		
		//cout<<"initially search_left: "<<search_left<<" search_right:"<<search_right<<"\n";
		assert(it->second <= upper_add_limit);
		assert(search_left >= i);
		assert(search_right >= i+1);
		assert(search_left <= search_right); 
		
		while(search_left <= search_right){
			//cout<<"search_left: "<<search_left<<" search_right:"<<search_right<<"\n";
			ll mid = (search_left+search_right)/2;
			ll x;
			if(a.find(mid)!=a.end())x=a[mid];
			else x=a[mid]=skim(mid);
			if(x <= upper_add_limit){
				best = mid;
				search_left = mid+1;
			}
			else search_right = mid-1;
		}
		
		//assert(search_left == search_right);
		
		bound = best;
		cur += a[bound];
		ret.push_back(bound);
		if(cur >= A && cur <= 2*A){
			for(int j=1;j<=i-1;j++)ret.push_back(j);
			answer(ret);
		}
		
		//The hard part! The binary search
		/*auto pos = upper_bound(a.begin()+i+1,a.begin()+bound,2*A-cur);
		if(pos==a.begin()+i+1)impossible();
		pos--;
		bound = pos - a.begin();*/
		
	}
    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