Submission #871222

#	Time	Username	Problem	Language	Result	Execution time	Memory
871222		Lib	Rarest Insects (IOI22_insects)	C++17	53.16 / 100	95 ms	856 KiB

insects

#include <bits/stdc++.h>
#include "insects.h"
//#include "stub.cpp"
using namespace std;
 
deque <int> PrevIndex;
int InMachine[2003];
int Permutation[2003];
//saving the answer of each iteration so that we won't accidentially binsearch something we've already calculated
int ok[2003];
int n;
int TypeCount;
int CurrentInMachine;
int l,r,mid;
 
int PossibleMincount(int cnt){
	while(!PrevIndex.empty()){
			PrevIndex.pop_back();
		}
	//Pushing insects inside the machine, keeping track of the ones being putted inside for this iteration of binary searching
	for(int i=0;i<n;i++){
		if(InMachine[Permutation[i]]==0){
			InMachine[Permutation[i]]=1;
			move_inside(Permutation[i]);
			PrevIndex.push_back(Permutation[i]);
			if(press_button()>cnt){
				move_outside(Permutation[i]);
				InMachine[Permutation[i]]=0;
				PrevIndex.pop_back();
			}
			if(PrevIndex.size()==(cnt-l)*TypeCount){
				break;
			}
		}
	}
	CurrentInMachine=0;
		for(int i=0;i<n;i++){
			CurrentInMachine+=InMachine[Permutation[i]];
		}
	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(!PrevIndex.empty()){
			InMachine[PrevIndex.back()]=0;
			move_outside(PrevIndex.back());
			PrevIndex.pop_back();
		}	
		CurrentInMachine=0;
		for(int i=0;i<n;i++){
			CurrentInMachine+=InMachine[Permutation[i]];
		}
		PrevIndex.clear();
		return 0;
	}else{
		//As every type of insects has at least cnt insects, the answer is at least cnt. Just return true
		while(!PrevIndex.empty()){
			PrevIndex.pop_back();
		}
		CurrentInMachine=0;
		for(int i=0;i<n;i++){
			CurrentInMachine+=InMachine[Permutation[i]];
		}
		return 1;
	}
}
 
int min_cardinality(int N){
	n=N;
	//Create a random permutation to fuck with shitty tests and achieve better query efficiency
	for(int i=0;i<N;i++){
		Permutation[i]=i;
	}
	srand(time(NULL));
	int Tempval;
	for(int i=N-1;i>0;i--){
		Tempval=rand()%i;
		swap(Permutation[i],Permutation[Tempval]);
	}
	//Remember to initialize as this is multitest
	for(int i=0;i<N;i++){
    InMachine[Permutation[i]]=0;
    }
    while(!PrevIndex.empty()){
			PrevIndex.pop_back();
		}
	//Phase 1: Determining the amount of different types of insects
	for(int i=0;i<n;i++){
		move_inside(Permutation[i]);
		InMachine[Permutation[i]]=1;
		PrevIndex.push_back(Permutation[i]);
		if(press_button()>1){
			move_outside(Permutation[i]);
			InMachine[Permutation[i]]=0;
			PrevIndex.pop_back();
		}
	}
	TypeCount=PrevIndex.size();
	r=N;
	l=1;
	//Phase 2: Binary search for the answer
	while(r-l>=1){
		CurrentInMachine=0;
		for(int i=0;i<n;i++){
			CurrentInMachine+=InMachine[Permutation[i]];
		}
		r=min(r,l+(N-CurrentInMachine)/TypeCount);
		mid=(l+r+1)/2;
		if(PossibleMincount(mid)){
			l=mid;
			//r=min(r,mid+(N-CurrentInMachine)/TypeCount);
		}else{
			r=mid-1;
		}
	}
	if(ok[r]){
		return r;
	}else{
		return l;
	}
}

Compilation message (stderr)

insects.cpp: In function 'int PossibleMincount(int)':
insects.cpp:31:23: warning: comparison of integer expressions of different signedness: 'std::deque<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   31 |    if(PrevIndex.size()==(cnt-l)*TypeCount){
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~

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