Submission #941635

#	Time	Username	Problem	Language	Result	Execution time	Memory
941635		shoryu386	A Difficult(y) Choice (BOI21_books)	C++17	0 / 100	1 ms	344 KiB

books

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


typedef long long ll;
    
long long gA, gK; 
void recur(int x, int taken, ll sum, vector<pair<int, ll>> takeitem, vector<pair<int, ll>> &items){
	if (x == items.size()){
		if (taken == gK && gA <= sum && sum <= 2LL*gA){
			vector<int> indices;
			for (int x = 0; x < (int)takeitem.size(); x++){
				indices.push_back(items[x].first);
			}
			answer(indices);
			return;
		}
		return;
	}
	
	recur(x+1, taken, sum, takeitem, items);
	
	if (taken != gK){
		takeitem.push_back(items[x]);
		recur(x+1, taken+1, sum+items[x].second, takeitem, items);
	}
}

void solve(int N, int K, long long A, int S) {
    // TODO implement this function
    
    //k books, sum of A
    
    //x, x+1, x+2, x+3, x+4, x+5... and so on
    
    gA = A; gK = K;
    
    int extrasum = 0;
    for (int x = 0; x < K; x++){
		extrasum += x;
	}
	
	//we want A <= x*K + extrasum <= 2*A
	//x*K + extrasum >= A
	//x*K >= A-extrasum
	//x >= (A-extrasum)/K
	
	ll target = (A - extrasum)/K + ((A - extrasum)%K != 0);
	//to do: check rounding
	
	if (A - extrasum <= 0) {impossible(); return;}
	
	int l = 1, r = N+1-K, ans = N+1-K;
	while (l <= r){
		int m = (l+r)/2;
		
		ll res = skim(m);
		
		if (res >= target){
			r = m-1;
			ans = m;
		}
		else{
			l = m+1;
		}
	}
	
	vector<pair<int, ll>> items; set<int> indicesInside;
	for (int x = max(1, ans-10); x < min(N+1, ans+K); x++){
		items.push_back({x, skim(x)}); indicesInside.insert(x);
	}
	
	for (int x = 1; x <= 10; x++){
		if (indicesInside.count(x) == 0) items.push_back({x, skim(x)}), indicesInside.insert(x);
	}
	
	recur(0, 0, 0, {}, items);
	
	impossible();
}

Compilation message (stderr)

books.cpp: In function 'void recur(int, int, ll, std::vector<std::pair<int, long long int> >, std::vector<std::pair<int, long long int> >&)':
books.cpp:11:8: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |  if (x == items.size()){
      |      ~~^~~~~~~~~~~~~~~

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