Submission #872307

#	Time	Username	Problem	Language	Result	Execution time	Memory
872307		Lib	Rarest Insects (IOI22_insects)	C++17	53.16 / 100	89 ms	1104 KiB

insects

#include <bits/stdc++.h>
#include "insects.h"
//#include "stub.cpp"
using namespace std;
int l,r,mid;
vector <int> PrevIndexIn,PrevIndexOut,RemainingInsects;
int InMachine[2003];
int n;
int TypeCount=0;
int CurrentInMachine=0;
 
int PossibleMincount(int cnt){
	//Pushing insects inside the machine, keeping track of the ones being putted inside for this iteration of binary searching
	mt19937 seed(63222221001217544);
	shuffle(RemainingInsects.begin(),RemainingInsects.end(),seed);
	for(int i=0;i<RemainingInsects.size();i++){
		if(CurrentInMachine==cnt*TypeCount){
			PrevIndexOut.push_back(RemainingInsects[i]);
			continue;
		}
		move_inside(RemainingInsects[i]);
		InMachine[RemainingInsects[i]]=1;
		PrevIndexIn.push_back(RemainingInsects[i]);
		CurrentInMachine++;
		if(press_button()>cnt){
			PrevIndexIn.pop_back();
			PrevIndexOut.push_back(RemainingInsects[i]);
			InMachine[RemainingInsects[i]]=0;
			move_outside(RemainingInsects[i]);
			CurrentInMachine--;
		}
	}
	RemainingInsects.clear();
	if(CurrentInMachine<cnt*TypeCount){
		//There clearly exist a type of insect with cardinality less than cnt, so the answer is less than cnt. Removing insects from last iteration.
		while(!PrevIndexIn.empty()){
			InMachine[PrevIndexIn.back()]=0;
			move_outside(PrevIndexIn.back());
			PrevIndexOut.push_back(PrevIndexIn.back());
			PrevIndexIn.pop_back();
			CurrentInMachine--;
		}
		RemainingInsects=PrevIndexOut;
		PrevIndexOut.clear();
		return 0;
	}else if(CurrentInMachine==cnt*TypeCount){
		//As every type of insects has at least cnt insects, the answer is at least cnt. Just return true
		RemainingInsects=PrevIndexOut;
		PrevIndexIn.clear();
		PrevIndexOut.clear();
		return 1;
	}
}
 
int min_cardinality(int N){
	//Remember to initialize as this is multitest
	for(int i=0;i<N;i++){
    InMachine[i]=0;
    }
    PrevIndexIn.clear();
    PrevIndexOut.clear();
    RemainingInsects.clear();
	n=N;
	l=1;
	//Phase 1: Determining the amount of different types of insects
	TypeCount=0;
	CurrentInMachine=0;
	for(int i=0;i<n;i++){
		move_inside(i);
		InMachine[i]=1;
		CurrentInMachine++;
		if(press_button()>1){
			move_outside(i);
			InMachine[i]=0;
			CurrentInMachine--;
		}else{
			TypeCount++;
		}
	}
	for(int i=0;i<n;i++){
			if(!InMachine[i]){
				RemainingInsects.push_back(i);
			}
		}
	r=(RemainingInsects.size()/TypeCount+1);
	int ans=1;
	//Phase 2: Binary search for the answer
	while(r-l>=1){
		mid=(l+r+1)/2;
		if(PossibleMincount(mid)){
			ans=max(ans,mid);
			l=mid;
			r=min(r,mid+(n-CurrentInMachine)/TypeCount);
		}else{
			r=mid-1;
		}
	}
	return ans;
}

Compilation message (stderr)

insects.cpp: In function 'int PossibleMincount(int)':
insects.cpp:16:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |  for(int i=0;i<RemainingInsects.size();i++){
      |              ~^~~~~~~~~~~~~~~~~~~~~~~~
insects.cpp:53:1: warning: control reaches end of non-void function [-Wreturn-type]
   53 | }
      | ^

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 28.16 / 75